I grew up in Cleveland, OH and my friends and I used to drive up to Niagra Falls all the time on the weekends (since the drinking age was 18) to party.
Don't really know of any places that are "family" friendly there....obviously check out the falls and if you can, take the tour where you put on the rain coats and go down into the falls. There are some cool museums there (wax museums too). it is fun there IMO. just walk around down near the falls and there is a ton of good stuff to do.
If you want to have a really great time, treat the family to a night at the Sundowner Strip Club. You wont be disapointed.