I suggest checking priceline or another one of those sites. You can get a good deal at the embassy out in La Vista but that is a bit of a drive to go somewhere in omaha.
Check out Coco Key Water Resort Hotel. My sister Took my niece and they had a blast. I also had some friends take their three kids recently and they had fun. May seem pricey but you get the all day water park pass and I think the zoo is fairly close.