OHSP

Give it time! It's very natural for interests to expand like this before they narrow. My advice is to be patient with your brain. As you do more research your interests will refine. If you're not applying to PhD programs this round then just try to put them aside for a moment and don't worry too much about closing doors on potential interests etc. 

Also I don't really know anyone who didn't find the first semester difficult (for so many reasons). Take the advice above re reading, talk to other people in your program, trust that you'll get the hang of it. I did too much of the reading in my first semester, not realizing that a) skimming is expected and normal and b) pretending you've read the whole book even though you skimmed most of it is also normal. 

To add onto this, just reading an article or two in any given area may completely destroy whatever interest you have. I ever so briefly had an interest in history of chemistry. Two articles cured me of that interest. 

Give it time! It's very natural for interests to expand like this before they narrow. My advice is to be patient with your brain. As you do more research your interests will refine. If you're not applying to PhD programs this round then just try to put them aside for a moment and don't worry too much about closing doors on potential interests etc. 

Also I don't really know anyone who didn't find the first semester difficult (for so many reasons). Take the advice above re reading, talk to other people in your program, trust that you'll get the hang of it. I did too much of the reading in my first semester, not realizing that a) skimming is expected and normal and b) pretending you've read the whole book even though you skimmed most of it is also normal. 

Give it time! It's very natural for interests to expand like this before they narrow. My advice is to be patient with your brain. As you do more research your interests will refine. If you're not applying to PhD programs this round then just try to put them aside for a moment and don't worry too much about closing doors on potential interests etc. 

Also I don't really know anyone who didn't find the first semester difficult (for so many reasons). Take the advice above re reading, talk to other people in your program, trust that you'll get the hang of it. I did too much of the reading in my first semester, not realizing that a) skimming is expected and normal and b) pretending you've read the whole book even though you skimmed most of it is also normal. 

Also I don't really know anyone who didn't find the first semester difficult (for so many reasons). Take the advice above re reading, talk to other people in your program, trust that you'll get the hang of it. I did too much of the reading in my first semester, not realizing that a) skimming is expected and normal and b) pretending you've read the whole book even though you skimmed most of it is also normal. 

Give it time! It's very natural for interests to expand like this before they narrow. My advice is to be patient with your brain. As you do more research your interests will refine. If you're not applying to PhD programs this round then just try to put them aside for a moment and don't worry too much about closing doors on potential interests etc. 

What subfield(s) are you interested in?

There will likely be a different admissions committee this year, and your application will be read in a new context — maybe they offered places to 6 Americanists and all of them accepted, in which case they might be offering a smaller number of Americanist spots this year, etc etc. My advice would be to get in touch with the prospective advisors who accepted you and to explain the situation—otherwise it’s going to be very strange for them to have your application re-appear on their desk. Professors are just humans and will understand (and if they don’t that might be a red flag anyway). As for recommendations I’d stick with what you had, unless your relationship with any of the recommenders has changed, or you’ve added anything significant to your CV. Good luck! 

I very strongly urge you to transition away from a metrics-based approach to thinking about the craft of professional academic history and that you not think in terms of "padding" this or that. Academics can tell when an aspiring graduate student is a true believer in the craft or someone who is playing to the numbers. This isn't to say that metrics are worthless. What I'm trying to convey is that in your OP you offer zero information about your interests or your skills.
You also present a view of personal professional relationships that is, at worst, cynical ("I am trying to pad my application a little bit....") In the strongest possible terms, I suggest that you rethink the relationship you have with the professor who offered you guidance on your paper. It's my hunch that you're on a different page, if not in a different chapter. That is, while he's talking about advancing the historiography of a field in a way that's beneficial to you as an aspiring professional, you're hearing "Here's a way to punch my ticket to a top twenty program." 

Not profoundly.  You're just getting the experience.
The most important thing is to focus on your writing sample and clarifying the questions you'd like to explore as a PhD student. I also would keep working on languages (or start on something related to your area of interest).  Finally, understand that there is no "reach/match/safety" in PhD admissions.  As with academia as a whole, much also depends on luck.  I also encourage you to look beyond the East Coast as being part of academia does require one to be mobile as possible, particularly if one is interested in a tenure-track professor job at the end.

There will likely be a different admissions committee this year, and your application will be read in a new context — maybe they offered places to 6 Americanists and all of them accepted, in which case they might be offering a smaller number of Americanist spots this year, etc etc. My advice would be to get in touch with the prospective advisors who accepted you and to explain the situation—otherwise it’s going to be very strange for them to have your application re-appear on their desk. Professors are just humans and will understand (and if they don’t that might be a red flag anyway). As for recommendations I’d stick with what you had, unless your relationship with any of the recommenders has changed, or you’ve added anything significant to your CV. Good luck! 

There will likely be a different admissions committee this year, and your application will be read in a new context — maybe they offered places to 6 Americanists and all of them accepted, in which case they might be offering a smaller number of Americanist spots this year, etc etc. My advice would be to get in touch with the prospective advisors who accepted you and to explain the situation—otherwise it’s going to be very strange for them to have your application re-appear on their desk. Professors are just humans and will understand (and if they don’t that might be a red flag anyway). As for recommendations I’d stick with what you had, unless your relationship with any of the recommenders has changed, or you’ve added anything significant to your CV. Good luck! 

There will likely be a different admissions committee this year, and your application will be read in a new context — maybe they offered places to 6 Americanists and all of them accepted, in which case they might be offering a smaller number of Americanist spots this year, etc etc. My advice would be to get in touch with the prospective advisors who accepted you and to explain the situation—otherwise it’s going to be very strange for them to have your application re-appear on their desk. Professors are just humans and will understand (and if they don’t that might be a red flag anyway). As for recommendations I’d stick with what you had, unless your relationship with any of the recommenders has changed, or you’ve added anything significant to your CV. Good luck! 

There will likely be a different admissions committee this year, and your application will be read in a new context — maybe they offered places to 6 Americanists and all of them accepted, in which case they might be offering a smaller number of Americanist spots this year, etc etc. My advice would be to get in touch with the prospective advisors who accepted you and to explain the situation—otherwise it’s going to be very strange for them to have your application re-appear on their desk. Professors are just humans and will understand (and if they don’t that might be a red flag anyway). As for recommendations I’d stick with what you had, unless your relationship with any of the recommenders has changed, or you’ve added anything significant to your CV. Good luck! 

The more seasoned posters here are probably tired of me banging on about languages for medievalists, but let's start there. Any PhD program of quality - and there's no reason to attend a PhD program which is not quality - will be looking for two modern research languages, typically French and German, in addition to Latin. They will have an abundance of candidates who meet this criteria. Exceptions to this rule usually come if an applicant has very good Latin but no French (everyone thinks French is very easy to acquire quickly), or if they have mastery of an unusual language (Greek, Arabic, Old Church Slavonic, whatever). 
These requirements exist for a very good reason: they are a starting place, and you will usually find you need to learn more languages as you continue your studies. Since my admission, I've picked up reading fluency in Spanish, Dutch, and Italian, for example. Without these skills, you can't get your head around the literature you need or do good work, nor can you work with primary sources. And that's why the requirements mark a program of quality - those who do not have the requirement are taking students who are not well-prepared to succeed. 
I say all this to highlight the point that language acquisition must be your primary goal before you apply to PhD programs, and that you should feel that you need to acquire not only Latin, but also German. Further, Latin is hard for most people to master. Even with 2 years of Latin in your MA, you will probably have to continue working on it as you go for your PhD. Finally, if you're still in the early stages of acquiring Latin, you can't really use it to work with primary sources, meaning you will have a weak writing sample. Consequently, I would advise that you take a year (or even two!) before you apply to MA programs working in the world and picking up the skills you need.
To your specific question on which MA programs, UCBoulder, Fordham, UChicago MAPSS, and St. Andrews are good programs, and I know a lot of people who have graduated from them to continue on to PhD programs. I don't have a fantastic opinion of WMU's program, but it's not the worst. Avoid Columbia.
I would add the following programs: UCLA (I think this still exists), Oxford, Cambridge, Harvard Divinity, Yale/Yale Div. 

Sounds like #2....   the keys are: 
For SOP: Demonstrate your awareness of the historiography in your areas of interest in Italy and science/technology
For Writing Sample: Demonstrate that you can skillfully engage both primary and secondary sources (the latter being historians' points and arguments).

Without seeing any of the papers, I'd suggest that you choose your strongest one - which should be engaging with primary sources and secondary sources when needed. There is no golden ratio. I applied to study Eastern European history in macro, but my paper was rather micro and its repertoire of primary sources was a single journal. 

You're going to have excuse my ignorance but is a 2-in-1 basically a tablet etc w a keyboard?? Maybe I'm a monster but I have a laptop, a desktop, and an ipad (the latter's the only one I bought new, the laptop's old and shitty but I need to be able to write outside of the apartment, and I bought the desktop cheap from craigslist when I started getting migraines from hunching over my laptop all week). It sounds absurd and excessive but I use them all pretty much every day. I read the majority of books and articles on my ipad -- before I began my phd, including during MA, I would never have imagined I'd be reading so much on screens--I was very much an "I need the physical book" kind of person. PhD life and qualifying exams have changed me (in many ways), and I now prefer e-books and pdfs for reading academic texts. Easier to mark up, file, and keep track of, especially if you can get an ipad type device w a stylus. I also often read from the ipad while typing notes on my desktop computer, and highly recommend a book stand for that purpose (I use the book stand for the paperback books I read, too). If I had to get rid of one of the three it would be the laptop, especially if you can get a tablet with a keyboard and a sufficiently large screen that it's not a pain when you need it for writing papers--my ipad's relatively small so I wouldn't want to use it for writing anything much longer than a response paper or email. 

It was the hardest decision I've ever made but I have declined Penn's offer and will be heading to Yale next year. 
I honestly still feel very conflicted, but I am incredibly excited for what is to come. 
Best of luck to everyone else! 

I would find this very, very off-putting--I was in a similar position w Penn a few years ago. My prospective advisor seemed amazing but she was also very near retirement and I couldn't imagine who would become my primary advisor if she were suddenly unable to advise me. I would highly stress the importance of a supportive team over a supportive individual (and I wouldn't put too much emphasis on big names, though this person also sounds like they have a record as a good advisor, so that's a bit different). To me, a stranger reading your post, it sounds like you'd be more secure at Yale, and feeling secure in your program is really important. 

I would find this very, very off-putting--I was in a similar position w Penn a few years ago. My prospective advisor seemed amazing but she was also very near retirement and I couldn't imagine who would become my primary advisor if she were suddenly unable to advise me. I would highly stress the importance of a supportive team over a supportive individual (and I wouldn't put too much emphasis on big names, though this person also sounds like they have a record as a good advisor, so that's a bit different). To me, a stranger reading your post, it sounds like you'd be more secure at Yale, and feeling secure in your program is really important. 

I would find this very, very off-putting--I was in a similar position w Penn a few years ago. My prospective advisor seemed amazing but she was also very near retirement and I couldn't imagine who would become my primary advisor if she were suddenly unable to advise me. I would highly stress the importance of a supportive team over a supportive individual (and I wouldn't put too much emphasis on big names, though this person also sounds like they have a record as a good advisor, so that's a bit different). To me, a stranger reading your post, it sounds like you'd be more secure at Yale, and feeling secure in your program is really important.