I went to school in Maryland and thus have a few friends doing prelim med years there.
GBMC - fairly nice although this year two of the interns didn't get their VISAs so they are short = more call, unhappier residents. It's probably just a fluke. The hospital is real nice though and the patients are more middle-upper class. q4overnight.
Mercy - good friend there who likes it. Says he works around 60-65 hours per week. You are in the inner city so you deal with LOTS of social issues but, come on no matter where you are, you deal with social issues. The issues are just a little different in the city. night float system. You get free food all the time. You get $5 for breakfast, lunch and dinner (doesn't carry over but, is more then enough for each meal). You wouldn't believe how great this actuallly is.
Franklin Square - real big on education and most of the residents were happy. This was my number one if I was going to do a prelim med (although, I didn't). The program director is really concerned with resident happiness and education and it shows. Daily noon conferences (with food) and morning report. I did my third year medicine there and all the residents were really close and look out for each other.
These are the only hospitals I know about of have friends at.