I'm sorry. I first saw this post about 3 hours ago and I'm STILL trying to come up with something.

I grew up across the river in Davenport and go back frequently to visit.
There are several John Deere related sites to visit. See
http://www.visitquadcities.com/site/page.php?page_id=64§ion=forvisitors
If you like baseball, Davenport has a farm team that plays right on the river. It's a beautiful setting for an outdoor ball game.
I suggest going to
www.quadcities.com,
www.quadcitychamber.com/visitor or
www.visitquadcities.com to get some ideas. There are river excursions on the Mississippi, gambling boats, historic tours, dinner theatre, symphony, museums... It depends what your interests are.
Oh, and if you like jazz the Bix Fest is a must!
Having collected Isabel Bloom statues for years, I have to say DO NOT GO TO THE ISABEL BLOOM place suggested in another post. The owners have destroyed what Isabel started and everything is now manufactured overseas, versus being handcrafted in the Quad Cities for decades. The manufactured ones are not as nice, IMO. There... off my soapbox now.

Oh, and the Des Moines, IA airport is 2.5 hours away from Moline and Cedar Rapids is about 1.5-2 hours. They are about the same size as the QC airport.