I'd definitely check out Twin Cities Bicycling Club - they put on a lot of rides (which, I believe, are open to non-members.)
If you'll be around for a while and want scenic and hilly, c'mon down to La Crosse, WI. It's a 2 1/2 hour drive or so, but there's plenty of good routes (road and gravel with little traffic) and fairly regular group rides. The Root River Trail might be a bit closer, and also worth checking out.