please take what i say w/ more than a grain of salt (i'm a prelim medicine in the city, at neither program), but...
NWU: an excellent medicine program. since they went to the ward system and instituted a night float, i think that they are in an excellent position to allow you the guided autonomy that used to only be the advantage of UofC and UIC (amongst academic programs w/in the city limits). from my friends at NWU, it seems that the ward system takes the interesting patients, the standard broing stuff goes to the hospitalist service (e.g. anticoagulation), and you don't have to touch bases w/ ten different attendings on your ten patients. be very cognizant of what you're getting into though, NMH is an extremely busy hospital and will continue to be one. many of the residents that i've met are very intelligent and motivated, and the structure of their day seems pretty cool. you also rotate at the west side VA at get to have that kind of change of experience. the nursing and ancillary staff are very good/excellent at NMH and pretty crappy at the VA, the hospital rivals many hotels for surroundings and service, and it's in a good part of town. their graduates place very well for fellowship. but remember that their patient population is mainly upper middle class to rich a**mofos (this is the kind of hospital where many of your pateints are having their Jaguars/BMWs/Mercedes/Bentlys/Rolls Royces... valet parked) that can be very demanding [but also have good insurance]. (i did interview there for my prelim).
UofC: again an excellent medicine program. surroundings and nursing/ancillary staff not the best, much more scut, often poor/indigent pateint population w/ the complicated and depressing physical and socio-economic issues of poverty. your coworkers are outstanding, and fellowship placement is great as well. had a reputation for being a bit malignant (at least for chicago), i dunno how it has changed. (i chose not to interview there for my prelim).
if i were you going into categorical medicine i would add in the personality of the program into the mix. it's so hard to quantify or even put into words, but figure out where you'll fit in best (did you like the residents/attendings/PD/chair, were they happy and enthusiastic about their program and experience, can you see yourself at that institution for 3-7 years, what kind of hospital do you want to work in and what patient population do you want to serve...)
hope this helps, and good luck. you'll be at a good place wherever you go.
