If you will have kids with you the Clock Tower Resort just added a waterpark in the last year (it is right out by the tollway). It isn't anywhere near the caliber of a Kalahari but it's pretty good. The Rockford Newspaper's website has a link for a special at
www.rrstar.com. Also the direct address is:
http://www.cocokeywaterresort.com/index.php?/Rockford/index/
It's near a lot of restaurants and stuff to do. (Magic Waters outdoor water park, CherryVale Mall, Movie theaters, mini put, go-carts, stores, etc.)