Depends on which part of KC.
Tabletop is a good central location, but if you don't really know the gamers there, talk with Phil. They're more of a closed gaming group.
31st Century has plenty of games running. They have
40k tourneys the first Saturday of each month. I think this weekend actually is 2k pt.
Otherwise, I've gone to other tourneys in Omaha (Game Shoppe) and Tulsa.
Hope to see you around!