If you are wanting to do international development work (like work at UNESCO) the best options by far are Stanford, Harvard and Penn. They have smaller cohorts and at Penn you have automatic internships at UN agencies. NYU and TC (and honestly really no other school even Stanford, Vandy and Harvard) provide that option. Harvard is definitely more economic/quantitative focused, Stanford is more academic/research, while Vandy is the most conservative and I would say least critical (based on their professors and posts). If you want to go the more academic route, Stanford, UCLA, and TC are probably the best. Further at Penn you can essentially get a full ride if you apply to the FLAS and GA-ships along with merit scholarships.
BTW TC's cohort is huge and word is it isn't what is used to be with several of their best professors having moved to other universities (Vavrus to Minnesota, Bartlett to Wisconsin-Madison).