Congrats on getting off both waitlists! I interviewed at both schools, and am happy to give you my impressions. First off, I'd say that cost isn't a big difference since they're both so expensive BUT the cost of living in DC is MUCH higher than in Burlington. I'm not sure how much UVM budgets for housing, but GW budgets $1100 just for housing and utilities, and that is definitely a conservative amount for the area (if you want to live alone near the school, I believe that studios start around $1300). That being said, DC is an incredibly dynamic and fun city compared to the very small (but cute) town of Burlington. Ditto with the weather since you're from CA - DC winters will be MUCH more mild than those in Vermont. I think a huge part of your decision may come down to where you can be happy. I loved UVM, but withdrew after getting waitlisted OOS because I realized I'd much rather live near a big city, and just couldn't see myself there. But I have VERY fond feelings for the med school. I definitely give UVM
and think anyone would have a great med school experience there.
I don't remember UVM's curriculum well, but I remember liking it a lot, and I tend to favor curriculums that are block, systems based with less lecture time. I do remember that they have amazing technology and online resources that were unbelievably impressive. The facility was nice and new, the student body laid back (also lots of non-trads in the class) and the administration nice and helpful as well.
GW has a very traditional curriculum with classes from about 8:30-5pm most days, although attendance is not mandatory, and many students take advantage of the note taking service and/or audio recordings of the lectures from what I've heard. The clinical opportunities in DC third and fourth year sound great, the med school class and patient population incredibly diverse, the GW hospital is nice and relatively new (2003?), and the med school facilities are nice too (if not brand new). Other than being in DC, GW's real strong points though, are the amazing opportunities they offer through their track program. I forget what they all are (emergency preparedness? alternative medicine? research?), but I am more familiar with their global health track and their health care policy track. I believe last year they sent 1/3 of the first year class to countries all over the world for their summer after first year, and there are relevant seminars during the first two years of med school, and a related research project in the third year. I believe they would also help facilitate fourth year abroad rotations if a student was interested. And the health care policy track has amazing opportunities in DC through the med school's connections (senators, CDC, etc.). Basically, the school makes the most of being in DC, and from what I've heard, is great at helping you find the right opportunities to match your interests.
I know that a number of CA students go to GW, and spend all of their fourth year (except three months at GW) in CA doing rotations there to up their chances at matching at a CA residency. I would think that UVM allows the same flexibility fourth year, but you might want to check on that. If I were from CA and wanted to return after med school, I'd ask about that for sure.
So, in sum, I think it will really depend on if you're a big city vs. small town person, how you feel about the curriculum, and if you feel particularly drawn to some of the special opportunities available at GW. Either way, I don't think you can go wrong. Both are great schools with great reputations, and both will make you a great doctor.
Good luck with your decision!