Hey, I wrote a "sales pitch" based on my first year at CMU thus far:
http://statisticalsignal.com/?p=258
I think if you're specifically interested in in machine learning, CMU gives you lots of options. We take two ML classes the first year, including "Statistical Machine Learning" http://www.stat.cmu.edu/~larry/=sml/which I think is quite unique. Lot's of our faculty are joint, and there's lots of opportunity to work with whoever you want here, everyone I've e-mailed is very friendly and open to communication/collaboration. (at least 3 of us work with ML professors, and there's a statistical machine learning reading group that is great: http://www.cs.cmu.edu/~aarti/SMLRG/)
I can't say anything about Michigan since I don't know too much about it, but I'm sure it's a great experience as well. Either way, you have two great options. I would give a good amount of weights to the visits, and see which department you feel more comfortable, the people there, etc...