I'm in exactly the same boat! MPAID, and MPA (development track) at Princeton. I'm also in to Tufts, who have offered me a travel grant to come to the open day... which happens to be day before MPAID open day, so hopefully visiting will give me a bit more clarity.
I initially thought Harvard was far and away my first choice, but I'm suddenly not so sure. Have you guys seen this post from Chris Blattman? - http://chrisblattman.com/2013/10/04/what-ma-mpa-or-mia-program-is-for-you/
I'm a bit scared of this 'leans to the macroeconomics' thing. I'm more micro focussed. BUT the Harvard brand is hard to argue with, particularly as a non-American. (If I tell people I've been admitted to Tufts they stare at me in polite non-comprehension...).
@jorexer ("I have a focus on certain sectors (agriculture, gender, microfinance), areas (Africa), and methods (impact evaluation, RCTs)") - We sound creepily similar! I've spent the last 3 years running RCTs in Africa. You're not by chance from the IPA/JPAL family are you?
Please keep me looped in to any Harvard vs. Princeton discussions!