I am a current intern at Wisconsin and have nothing but great things to say about the program. Last year on the interview trail, I thought it was one of the most well-balanced programs I saw and stand by that after spending 7+ months here. You get great exposure to all subspecialties without getting too much of any of them. You get a life outside of residency (except on the Trauma service, as OrthoDoc already pointed out) and you're living in a fun town to enjoy that time. I think the operative experience here is excellent. We don't log as many cases as some community programs, but we have enough operative experience that 2 of our chiefs this year are going straight into private practice. What really separates this program is the group of residents. There's not a single resident in the program I wouldn't enjoy going to have a beer with right now. I'm clearly biased because I am here, but I interviewed at a lot of great programs and this remained one of the best programs I saw last year. If you have more specific questions about the program, I'd be happy to answer them. I know a couple of us interns posted our lists and thoughts on programs last year in the ROL thread.
I did not interview at Michigan or UNC, but did at Vermont. I thought Vermont was also a great program with a fun group of residents. Burlington is a pretty cool town, but one of the only places colder than Madison. The only thing they lack is a tumor surgeon. Other than that, if you would like living in Burlington it's a hidden gem of a program.