Ken et al - If you're looking for fat bikes, and want to see more than just one in a shop, come down to World of Bikes. We probably have the largest selection in the area, including the ever popular Surly Moonlander, the fattest of the fat! Adam, the guy you met the other night at the ICORR party swears by fat bikes, year round.
Also, if you watch facebook, there's always the Friday Night Fatty Ride in Iowa City. "Like" the World of Bikes page for details. Usually, there's a dozen or so fatties riding, and I'm sure one of them will let you try theirs out.
- Chucky V
aka c wagon
Bike - Gary Fisher X-Caliber '09
Crank Bros Eggbeater SL pedals
Salsa Pro-Moto Carbon Flat bar
Bontrager Race XXX Lite stem