GovAffairs

The Art of Applying. Although I did not hire @Connie @ TheArtofApplying she has been an amazing resource and so has that organization.

Hello @hj2012 , thank you for the links. They are quite useful. Actually, I did try to search on google but got really confused because of several conflicting information. Hence, I came to this forum to ask more knowledgeable and experienced people. Thanks again! 

The Foreign Policy ranking shows overall reputation of the IR programs among policy wonks and academics and jives with my personal experience: http://foreignpolicy.com/2015/02/03/top-twenty-five-schools-international-relations/
You might also find this list of MPP programs (not IR specific) helpful: https://www.usnews.com/best-graduate-schools/top-public-affairs-schools/public-policy-analysis-rankings
Google is your friend! There's lots of info out there. 

Reading closely through these forums helped me understand each program's personality. Also requesting literature from them, or class profiles when they aren't published online (average age, GPA, GRE, etc...). I LOVE this resource: http://portal.publicpolicy.utoronto.ca/en/Pages/index.aspx
It doesn't explore reputation so much as curriculum. Look at schools' websites and browse through faculty profiles to see what sort of appointments they have and where their research is published. Look through LinkedIn to see where graduates are working, or where students are interning. It is time-consuming! Make a nice spreadsheet
Also! -- I sat at bookstores looking through peterson's/USNWR stuff and they were NOT helpful. Maybe for law and biz, but not these programs.

I'm going to shamelessly plug for my school (CMU Heinz). I've posted some pros and cons here: 
 
But also, I'd like to echo the above posters. Rankings (esp. USNWR) are NOT helpful for public policy applicants. UNSWR has Indiana ranked above HKS and WWS, and schools like SAIS aren't even included. Yet HKS, WWS, and SAIS grads are the ones getting into the most influential employers. Several things that matter more than rankings include:
The actual reputation of the school. A good rule of thumb is to go by the general reputation of the school. I.e. you can expect Berkeley grads to be hired before Indiana grads, all else held equal, with a few exceptions. The curriculum and focus of your school. Some schools, like UPenn Fels, are heavily focused on local government. So if, for example, you wanted the UPenn name but didn't want to go into local government, you'd be better off just going for Wharton or an M.S. program instead. Also schools' coursework may not help you prepare you for what you want to get into if you're not careful. If you want to go into data-focused policy but you also want Georgetown because of its name, then you may want to choose CMU instead. Location. DC or NYC will help. And etc... All that being said, there are nine schools that I repeatedly hear of, have strong reputations in the policy fields, and have enough breadth to appeal to a wide range of students. I've put an asterisk next to schools that provide more financial aid than others. Note though that Berkeley and Michigan aid typically comes in the form of assistantships that you don't get until after you commit. They are listed below in no particular order:
Princeton*, Harvard, Columbia, Chicago, Duke*, Georgetown, CMU*, Berkeley*, Michigan*
A firm sent me the list in a survey concerning my perceptions of the reputations of various public policy schools and I felt that the list almost perfectly mirrored my experiences. I can't think of another school to add to the list and I can't think of a school to take off it.
Of course, take it with a pinch of salt. If you're comparing Duke to American and the DC location factor is extremely important to you, the list doesn't imply that you should ignore DC or the scholarship that American may give you. The list also doesn't focus on schools from an international affairs stance (e.g. SAIS and Tufts Fletcher should be on there), but for that, I've actually found the Foreign Policy rankings to be somewhat helpful.