I hope you're not planning on traveling I-29 since it's mostly under water right now, both north and south. College world series currently going on until the 29th-30th so most places pretty full. As far as Casino's go, two of them are under water and the third, Horseshoe Casino, has a real nice new RV area. Bit south of Omaha, Gretna, has a decent KOA and then there is Mahoney State Park about 15 miles south of Omaha on I-80. If you get to town while the series is being played you'll definitely want to check it out. It's a really big deal around here. Lots to do and lots of fun.
2013 Winnebago Aspect 27K
E450, V10, CRV, Blue Ox