Gretna KOA is WAY overpriced. There is a private owned CG just west of the KOA on I80, not sure what it is called. Louisville SRA is very nice, spread out, but a distance from the ballpark. Checkout the Zoo, Old Market, Pedestrian bridge, breweries, good restaurants, casinos (one has a cement CG that would be 5mins from the ball park), Mahoney SP (even if you don't camp there), many large outdoor shopping areas, UP RR Museum and Dodge House in Co Bluffs. And don't go to lunch with Buffett, he will make you pick up the tab. :)