I lived in Columbus for 9-10 years and had a great time. Of course, that was in my 20s so it was hard not to have a good time.
If you're going downtown, hit the Short North. Go to Dagwoodz on High for a quirky neighborhood bar with great food. Then you can drive up High Street to the OSU campus and visit the Wexner Center for the Arts. Drop by Larry's for a beer and basket of peanuts. Then drive a little farther up High Street to the Park of Roses along the Olentangy River.
That's all I have time for right now.
Mike