It depends where you live in Center City. You can always bike it, and if you live between 20-23rd, you can easily walk it (Philly is a bit strange the next street after 23rd is 30th, not 24th).
Shuttle is also an option, but it may be a bit of pain because it runs every 15-20 minutes...
So, if you live in center city, my advice is look into housing in the twenties...I think a lot of med students live in 2200 Chestnut.
As far as west philly, I currently live there, adn live in an amazing building...My apt is as expensive as center city, but its on 39th Street, which is three blocks away from Stemmler Hall, so its really close to campus. You do have to be careful with west philly. Some housing sucks, but other places are really nice. Ideally, if possible, I would suggest making a trip to philly if you can. Otherwise, do you knwo anyone in Philly who could check out a few places that sould reasonable?