Stop in Grand Forks to watch the Fighting Sioux play at Ralph Engelstad Arena. That arena will blow you away, nothing like it at the college level.
The West Acres mall in Fargo has the Roger Maris museum - a pretty extensive museum for a mall and kind of cool.
Mall of America is worth stopping in at Bloomington. Try to catch a Minnesota Wild game when you're there too (in Saint Paul) - the nicest rink in the NHL in my opinion. If you're there for a few days, go see the Golden Gophers. Amazing atmosphere.
Lots of cool things in Chicago. Millennium Park is really neat during the evening. Place to eat there, go to Gibson's Steakhouse. Best steak I've ever had.
That's as far as I've driven.