I interviewed at both CHOP and St. Chris, and I really liked both. CHOP obviously has amazing facilities, and everyone was very smart. It is pretty fellow-driven, and of course all the residents there say they prefer this, because it allows them to go to a fellow for teaching and to call in the middle of the night, rather than having to disturb an attending. It's a personal preference. St. Chris residents seemed to have much closer relationships with the attendings, which I kind of prefered. The facilities are good there too (free-standing, etc). One down side I would say is that all orders at St. Chris are hand-written at the bedside, rather than on the computer. At CHOP, all that stuff is on the computer, and apparently by the end of 2008 they are going to have all notes on computer too.
As far as the neighborhoods go, St. Chris is right near the ghetto. The residents said they never felt unsafe or anything, which I understand because it's not like you go hang out down the road from the hospital. It has a very high Spanish speaking population as well. CHOP was closer to the center city and right down the street from UPenn, which is a pretty nice area. I think a few blocks the other way is less nice, but I didn't see much of it. I think either way you're going to have pretty impoverished patients, but I think you'll feel safe no matter what.
Oh, one last thing...St. Chris pays for parking for the residents, at CHOP they don't. Let me know if anyone has any specific questions about either of the programs (I'm not interviewing anywhere else near Philly) and hopefully I can help.