Are you going for the day, or camping there. We went a couple years ago with my 3 kids. As for the outside stuff...there is a great area for little ones...a big splash pad, the wave pool and water slides... then down below there was a lot of different things, the bumper boats, mini putt, batting cages and climbing activities, also there are go-carts. I would think if it was rainy that the inside would be a zoo. There is a large jungle gym sort of climber, and some arcade type games to play. Definitely more stuff outside than indoors.
My boys were around 3, 10 and 13 when we went there. They all found something that they liked to do, but we did need to split up as the 3 year old didn't want to do what the 13 year old wanted to do.
Hope this helps...have fun!!!
Sue