Don't know if your still looking but when I took the family to the Falls we stayed at the Great Wolf Lodge. It was a lot of fun and the kids really loved the water park.
We haven't been to any of the other Great Wolf Lodges before but this one had rooms that were made up like log cabins and although the place is huge, it doesn't feel that way... Except for the waterpark, it was really big and apparently is only open to guests of the hotel which meant it was never to busy to have fun.
I'm not sure what your budget is, the rate we paid was a little over $200 a night for the family but that also included use of the waterpark for the stay so we feel that it was worth it.
Have a great time!
Shop Around... by: Joe
Check out expedia.ca, travelocity.com and other travel websites. They often offer deals if you stay multiple days.