Did the Indiana part of this, from west to east last summer. Picked up US24 off I-57 in Illinois, through Watseka IL (a really funky little town, would like to have spent some time looking at it) and on eastbound to Fort Wayne. IF you're in a hurry, this is NOT the route for you! We were in a bit of a hurry, but weren't towing for that trip. There's a number of little towns in Indiana between the IL line and Logansport IN, where the road is 4 lane all the way to Fort Wayne. Those little towns will slow you down, but if you ain't in a hurry, it don't matter!
I'd do that route again, IF I were towing and taking my time, and doing only 400 or so miles a day. Driving on secondary roads can be fatiguing in a different sort of way from Interstates. You have to pay attention more, and it's not so mind numbing as the Interstates.