If you are taking I90 into MN, and have time to allow a slower drive, just after crossing into Minnesota, take the Winona exit north.
You'll hit a lot of small towns along the Mississippi, very nice drive. You'll see a lot of eagles along the way. You'll go through Wabasha, home of Grumpy Old Men.
The next option would be the Rochester exit off I90.
If you plan on taking interstate all the way, you'll go to Albert Lea on I90, then I35 north. It's OK if you like looking at fields.
ETA:
Coming from IL, you could just take 94 the entire way and I'll leave it to the Wisconsin members to chime in for sites along the way.
Are you interested in site seeing in the Twin Cities? Fort Snelling is near the airport, the State Capitol is a side trip.
When in the Mall, you need to find home plate from the old Met stadium, at least I think it's still there, I haven't been to MOA in probably 15 years.