I'm in Wichita, but have visited a few of the KC shops. Bike Source is probably the best in terms of inventory and breadth. The Trek store at SM Pkwy and I-35 has lots to see, too, but it's all Trek, of course. The others I've stopped at were either high end boutiques with little on the floor or a little run-down with cheap inventory. Several stores report to carry a lot of the non-big-4 brands, but it just means they'll order one for you.
Haven't looked north of the river or east of town.
All in all I was disappointed, outside of Bike Source and the Trek Store. Capps in Topeka is a good one, and Wichita has 2 or 3 as good.