I have heard fabulous things about Great Wolf Lodge (we have one fairly close to us in the Poconos) and know that my kids would absolutely love it if I got this deal!
Right now you can get a Great Wolf Lodge Vacation package for as low as $149! There are deals available at 10 different locations and most are for a 1-night stay with up to 6 water park passes.
Make sure that you read the fine print before you purchase your getaway package. Most of them have limitations on when you can redeem your Groupon and prices vary by location and when you want to visit.