Regarding northwestern, if you are from a Chicago medical school, you can definitely get an interview without rotating. I did and so did another from my school (whether we could have matched, who knows?, we both matched higher on our rank lists). If you are not from a Chicago medical school, than what was said above is probably true.
Rush definitely interviews nonrotators. There were at least 20 nonrotators that got interviews. In my interview, I was told that their residents are about 50-50 in regards to rotators and nonrotators.