Which part of Indiana are you traveling to? The route I will give you is one we take when we are traveling to the South, and we live far west of Chicago, so driving into Chicago often takes us out of the way of where we want to go anyway! Plus, we have sat in traffic at the 80/94/294 etc. mess for over 3 hours before, so avoiding Chicago is what we strive for, too! However, you will end up in central Indiana, so if you want northern Indiana, this won't work.
Take 90 to 39 (Rockford). Go south until you get to 74 (Bloomington). Go east into Indiana. Traffic really moves, so be prepared to NOT travel under the speed limit. My DH drives only 5 miles over, and is constantly tailgated on these highways, so I tend to drive them, and go about 15 over. Just a caution!
Whichever way you choose, hope you have a safe trip!