I know very little about Indiana, but here goes:
Iowa is in Iowa City, a college town with quite a few bars and a good assortment of restaurants. Because it is in a college town, sports are relatively big if that's your thing. Cost of living is pretty low also, you can get a nice 2Br (away from campus) for ~800/month.
Iowa as a medical school has quite a bit of research going on, and there are many opportunities for medical students to get involved with this. Also, there are many service opportunities through the college (mobile clinic) and in the city (free clinic). The facilities are very nice, with several newer buildings at center of the medical campus (MERF, CBRB, etc.).
USMLE scores are likely to be around or above average, but this isn't a good deciding factor on where to attend a school. Going to a school isn't going to automatically raise or lower your USMLE scores, you will be the one doing that.
The hospital (UIHC) is a pretty well known hospital and is nationally ranked. It's no Hopkins or Mayo, but it's pretty good, especially in optho, ENT and ortho surgery. You will get diverse cases at UIHC, no doubt.
If you are in-state for one of the schools, choose the cheapest one. I doubt either school would keep you out of an ultra competitive residency if you put in the effort. Neither school is going to magically open doors for you either the way Hahhvahd might (though some would argue against this).