We went a few years ago and stayed at the KOA on Lundy's Lane on the Canadian side. I was very happy with the campground. It is a couple miles up the road from the falls, but there is a city bus service that stops right at the campground entrance and runs constantly - seemed very inexpensive to me.
As another poster said, Niagara Falls is a lot like Vegas - or as I thought, kind of a twisted Disney World. All those pictures you see of the falls are from one angle only.
If you can arrange it, eat at the Skylon Tower! We had three families, ate at the the buffet section, put a dent in their profits, and the food was really good. Restaurant overlooks the falls, and you can go up to the outdoor viewing area after you eat.
Maid of the Mist is pretty cool, worth doing, but quick.
There is a ton of stuff to do and see. I took my son and his friend to see the power generating station a few miles up from the falls. Very cool, go down in an elevator like 27 stories to see the generating section. I found it very interesting to learn that they moved the generating station away from the falls to actually get more power.
Niagara Falls is a tourist trap, but is a lot of fun and worth seeing at least once.