We went about 10 years ago and stayed on the Canadian side at the KOA on Lundy's Lane basically just up the street from Niagara Falls. A city shuttle bus would stop at the entrance to the campground, so it was really easy to visit downtown Niagara without having to drive. I am not sure if anything has changed.
Lots to do there. We had dinner at the Skylon Restaurant overlooking the falls, and it was great - both food and views.
My son and I visited the power station up river and thought it was neat. They have a short tour, you go down 27 stories to see the generators.