Well, I'm going to Vandy and know nothing about Pritzker, but I can make a little pitch for Vanderbilt.
1) If there's one thing that school emphasizes, it's approachability. Every student talked about how nice and easy to talk to the faculty and administration are, and they certainly brought that out at Second Look. Fwiw, our future classmates are amazing, fun people that I really look forward to spending 4 years with, and the upperclassmen were pretty awesome, too.
2) I have a couple of friends at Pritzker and my boss went there for med school, and they actually advised me against applying. They felt the school was in decline (however, I do believe they're changing things around a lot this year, what with the smaller class size and stuff I think the "feel" of the school is going to be quite different) instead of becoming more and more present in the national scene. Incidentally, this is n=3, one of whom went to Pritzker a bunch of years ago, so take it with a HUGE grain of salt.
3) Vandy is true P/F the first year, and they add an honors second year (although everyone assured me it doesn't make the class more competitive...but who knows, I suspect most med schools are competitive to an extent). I definitely like the P/F thing cause it seems less stressful on a day to day basis.
4) Every single hospital is on the same campus, which is also the undergrad campus and the grad campus of every other grad school. This is HUGE, as far as I'm concerned, cause I don't want to have to drive around town madly third year or have to move away cause my clinicals are on the other side of the city (I'm looking at you, Emory!).
5) I love that Vanderbilt is a big fish in a pretty small pond. The mayor of Nashville came to talk to us (ahem, campaign, ahem) about the city at second look, and it just made me realize how big a deal Vandy is in those parts. Their trauma center covers just about most of Tennessee and thereabouts, according to the LifeFlight people. I like that there aren't any other MAJOR academic institutions around to compete with for resources, great physicians, etc. This is really different from Boston and New York, which are the cities I'm most familiar with, and I assume Chicago is similar in that respect.
6) I hear U Chicago is stunning, so I'm not sure whether this is really a useful argument to make, but Vandy is just lovely. The anatomy lab is kind of ridiculous. The library is huge and bright and gorgeous. I like that it's right by "downtown" (although granted, Nashville's downtown isn't really on par with a huge city's downtown, but ya know, how much time will you really have to go to a museum anyway).
K, this is all I can come up with. Rebuttals are encouraged.
Really I haven't made a decision because I'm not supposed to be thinking about med school (or being on SDN for that matter) at all until after finals. 
