I totally agree with Chubby. For me, geography was at the very bottom of the criteria list. I'm an adult and don't need to have my mommy within driving distance to keep it together, my friends from college are all scattered anyway, and I think I'd probably become a much better doctor for working with a population I'm not necessarily familiar with than if I just stayed home and hung around the place I'm most comfortable with. I figure I'll be spending most of my time on campus studying anyway, and on weekends people tend to gather at the same 3 or 4 bars (this happens even when you live in a huge city), so ultimately, geographic location is irrelevant.
On the other hand, while geography doesn't really matter, I think some people are really freaked out by freezing cold rural places and some are really freaked out by major urban centers. You also don't want to become a shut-in because seeing cows makes you have a panic attack or you don't like rude New Yorkers.
I think for me, cost was huge, and the campus/facilities were huge. Forget the city I'm in, I'm gonna be LIVING on that campus. Am I comfortable walking around there alone at night? How close are students' apartments and how expensive? Do the lecture halls feel claustrophobic? Is the hospital in disrepair? Is there a nice, airy library for me to study in for 10 hours straight? Obviously this is a matter of personal preference and plenty of people don't care for pretty campuses and safe neighborhoods, but it was one of my major criteria.