I just discovered this site, and jumped on your thread because I am also trying to plan a road trip out of Chicago. I'm actually from Columbus, so I thought I'd weigh in.

Cbus isn't a bad place. It's especially fun if you know someone going to Ohio State, who can show you around to all the cool hole-in-the-wall places on campus. But if you don't, I'd say there are still some fun things to do. the Ohio State Fair is coming up in august, if you're into that. There's a couple of jazz festivals in the summer. There tends to be great theatre in the area, if you're into that, and the Short North (downtown, High Street) is a fun place for nightlife. I enjoy sometimes lesser-known gems like the Franklin Park Conservatory (lots of plants, a butterfly room - I once saw a Chihuly glass exhibit there), the art museum downtown, and the Ohio Historical Society (I forget where it actually is, but I went there on a field trip once). North Market is a fun place to eat. The Columbus Zoo is, I think, the home of Jack Hanna and is pretty fabulous.

I don't think it's super exciting, but I've lived here most of my life. You'll pass some fun things on the way - the Indiana dunes and (no, I'm not kidding) the RV/Motor Home Hall of Fame. You'll also pass the University of Notre Dame if you take 80/90 S, which is beautiful and the second largest tourist attraction in Indiana.

Anyway, hope this helps. :)