BabyScientist

As a Californian, before applying to grad school, I wouldn't have known UNC was even remotely a notable school, but I've always known Brown. 

My major was almost entirely pre-med, and I never wanted to go to med school. No grad program will penalize a good applicant for what their science major was, whether or not they intended to go to med school. I did have a few interviewers ask me if I was ever pre-med, but it didn't matter.

Have you reached out since to the PIs you clicked with? Are they both well established, or newer faculty? Would one have more power/resources/connections that could help you get a job later? Have you spoken with current students extensively? Considered how much you liked the current students and the people in your interview class (aka your future classmates)? Are there any professional development opportunities one school offers that the other doesn't (workshops, conferences, etc)?
When it comes down to it, you can't go wrong either way. 

Bottom line for any grad program anywhere, go to the one that is the best fit for you. 

Would you rather be in LA or Seattle? I don't know about Seattle, but housing is super expensive in LA.

Taking some time to work in your field of interest is ALWAYS a good idea. Programs will be much more impressed with someone who has proven that they know what full time work in a lab for an extended period of time is like. Not too long, of course, but I was a lab tech for a year after graduating before I applied to grad school (meaning it'll have been almost 2 years by the time I'm in grad school), and my most significant scientific experiences have been during that time. Undergrad research experience is experience, of course, but it isn't very representative of full time lab life. My past year and a half or so has been completely different from the part time experience I had in undergrad, and even the full time summer work I did.
I recommend being a lab tech for at least a full year, so you have something to show for it, or maybe considering a post-bacc program, such as the IRTA at the NIH (I don't think one is necessarily much more beneficial than the other). And, wherever you go, emphasize to your PI from the start that you are interested in pursuing a PhD and are serious about completing your own projects, getting on publications, and presenting at conferences. Those are the things that will prove to graduate programs that you're ready to take on 5+ years of research.
Good luck! 

Haven't even done all my interviews yet and already freaking out about not loving schools I thought I wanted to go to, loving schools I didn't think I wanted to go to, deciding between prestige and comfort, and figuring out how my decision will affect my significant other's career.

Personally, it wasn't things I asked or did, it was how I felt or things I observed. At one, the current students spent the first night dinner complaining about the commute, the free shuttle, the crowded gym, etc. Didn't get happy vibes from them. At another, I just felt like the current students weren't really my crowd, neither were the people in the recruitment class. I didn't feel like I would fit in. Only question I asked at one place that turned me off was whether or not they had outreach programs. The director of the program literally asked why I cared.....

Of all my interviews, there were 2 I was most excited about and 2 I was least excited about (and considered canceling). Those opinions flipped entirely after my visits. Bottom 2 became top 2 and vice versa.
It was vibes. 

Personally, it wasn't things I asked or did, it was how I felt or things I observed. At one, the current students spent the first night dinner complaining about the commute, the free shuttle, the crowded gym, etc. Didn't get happy vibes from them. At another, I just felt like the current students weren't really my crowd, neither were the people in the recruitment class. I didn't feel like I would fit in. Only question I asked at one place that turned me off was whether or not they had outreach programs. The director of the program literally asked why I cared.....

Of all my interviews, there were 2 I was most excited about and 2 I was least excited about (and considered canceling). Those opinions flipped entirely after my visits. Bottom 2 became top 2 and vice versa.
It was vibes. 

Of all my interviews, there were 2 I was most excited about and 2 I was least excited about (and considered canceling). Those opinions flipped entirely after my visits. Bottom 2 became top 2 and vice versa.
It was vibes. 

Haven't even done all my interviews yet and already freaking out about not loving schools I thought I wanted to go to, loving schools I didn't think I wanted to go to, deciding between prestige and comfort, and figuring out how my decision will affect my significant other's career.

Haven't even done all my interviews yet and already freaking out about not loving schools I thought I wanted to go to, loving schools I didn't think I wanted to go to, deciding between prestige and comfort, and figuring out how my decision will affect my significant other's career.

Haven't even done all my interviews yet and already freaking out about not loving schools I thought I wanted to go to, loving schools I didn't think I wanted to go to, deciding between prestige and comfort, and figuring out how my decision will affect my significant other's career.

Haven't even done all my interviews yet and already freaking out about not loving schools I thought I wanted to go to, loving schools I didn't think I wanted to go to, deciding between prestige and comfort, and figuring out how my decision will affect my significant other's career.

A week isn't too bad. I forgot to as well and did it like a week and a half later. Only email those with whom you felt you had a great conversation or who you really liked.

Same thing happened to me. Ask him about his research. Ask any questions you can to make sure you understand, just to show interest. To carry the conversation, ask general questions about the program and the way his lab functions. That's what I did and it went well.

Same thing happened to me. Ask him about his research. Ask any questions you can to make sure you understand, just to show interest. To carry the conversation, ask general questions about the program and the way his lab functions. That's what I did and it went well.

This is a good point.
I think it also detracts from the conversation. You want your interview to be a conversation, not something you had to bring props for. If anything, I would just be ready to draw out the diagram so you can explain it better only if they seem to need the visual.
 

This is a good point.
I think it also detracts from the conversation. You want your interview to be a conversation, not something you had to bring props for. If anything, I would just be ready to draw out the diagram so you can explain it better only if they seem to need the visual.
 

I have 6 interviews lined up, one is still pending, so maybe 7.
I work full time, and my job is super understanding about taking time off for this. I also have a ton of paid time off saved up, so I'm still getting paid for the days I'm missing. I have 3 interviews in a row in late February, so I'll be out for almost 2 full weeks.
My mistake is that all my interviews are across the country, so I've got a lot of loooong flights coming up.
The reason I accepted all if them is because I felt like I had to give every opportunity a shot. What if you go to your top school interview and hate it? Or go to your last choice and love it?
I just had an interview at my 2nd to last choice school, and I loved it more than expected. If I had declined any interviews, this would have been one of them, so I'm really glad I didn't.
But, at the same time, if you've got like 10 interviews, it would be exhausting and some probably wouldn't go well. Just keep in mind that you'll have to choose between all of these schools eventually.

After having my first interviews this weekend, this is what I came away with:
I didn't really need to know much about the faculty's research, just the general idea of what their research focuses on. A few told me about their research, but the interview was focused on my experience, and I didn't really get the opportunity to comment on their research, because it was usually toward the end of the interview.
So long as we were talking the entire 30 mins, it was a successful interview. Either I went on and on about my research experience, answering their questions throughout, or we sparked a random conversation about almost irrelevant subjects and kept on that track the whole time. With one guy I talked about the difficulties of getting patients into studies for half the time (I do molecular biology research, not anything clinical). Whenever I felt a lull in the conversation coming, I thought of a question to ask. With one we just spoke about my general interests, including non-science related interests.
Almost every interviewer asked me to tell them about my research experience. In one of the first ones, I decided to start from the very beginning of my lab experience (5 years ago), which I quickly realized was a bad idea. It was my earliest experience, and although I know the big picture of the experiment and my part in it, I don't have a firm grasp on everything, so I couldn't answer a few of the questions about it. What I did in the rest of my interviews was immediately bring up my most recent, most significant research experience, and reference my prior experiences where appropriate.
There was a panel interview for 20 mins with the entire admissions committee (6 people). It was intimidating at first, but actually ended up being the least stressful interview. I just talked about my research the whole time and they asked questions about it throughout.
Finally, wear comfortable shoes. They don't have to be the most stylish, so long as they're formal enough and you can spend a day in them walking up and down hills (my interviews weren't all on the same side of campus).
The director of the program/head of the admissions committee told me I did really well, so I'm coming away from it assuming I did something right.

After having my first interviews this weekend, this is what I came away with:
I didn't really need to know much about the faculty's research, just the general idea of what their research focuses on. A few told me about their research, but the interview was focused on my experience, and I didn't really get the opportunity to comment on their research, because it was usually toward the end of the interview.
So long as we were talking the entire 30 mins, it was a successful interview. Either I went on and on about my research experience, answering their questions throughout, or we sparked a random conversation about almost irrelevant subjects and kept on that track the whole time. With one guy I talked about the difficulties of getting patients into studies for half the time (I do molecular biology research, not anything clinical). Whenever I felt a lull in the conversation coming, I thought of a question to ask. With one we just spoke about my general interests, including non-science related interests.
Almost every interviewer asked me to tell them about my research experience. In one of the first ones, I decided to start from the very beginning of my lab experience (5 years ago), which I quickly realized was a bad idea. It was my earliest experience, and although I know the big picture of the experiment and my part in it, I don't have a firm grasp on everything, so I couldn't answer a few of the questions about it. What I did in the rest of my interviews was immediately bring up my most recent, most significant research experience, and reference my prior experiences where appropriate.
There was a panel interview for 20 mins with the entire admissions committee (6 people). It was intimidating at first, but actually ended up being the least stressful interview. I just talked about my research the whole time and they asked questions about it throughout.
Finally, wear comfortable shoes. They don't have to be the most stylish, so long as they're formal enough and you can spend a day in them walking up and down hills (my interviews weren't all on the same side of campus).
The director of the program/head of the admissions committee told me I did really well, so I'm coming away from it assuming I did something right.

I would respond after filling out the form. Just say something like "I've completed the form and look forward to meeting you at the interview." For me, personally, it's like insurance that they know I'm interested in case something happens and the form doesn't go through. Also shows enthusiasm.