Personally I'd suggest the cities getting Google Fiber. Having lived in Kansas City, I think it's in a ripe position to foster a solid startup community, while still having a pretty solid nightlife, great restaurants, walkable neighborhoods, a many-nonstop-destinations airport, and an incredibly low cost-of-living.
Existing startup community can be found mostly via http://siliconprairienews.com/ or incubators like http://betablox.com/