We went on a day trip from Toronto to see the Niagara Falls and our trip included lunch at the Sheraton Penthouse Fallsview Buffet (all you can eat) - it has a great view, you are nearest to the American Falls and get a super view of these from the full length windows in this restaurant, it also has a small balcony which is great for taking photos - a professional photographer takes over the balcony on and off, but our server tipped us off when the photographer was on a break so we could take our own photos

!!
My sons and DH also took a helicopter flight over the Falls - beware - if you are sitting in the middle seat it is difficult to see, but the DS and DH on the outer seats really enjoyed the experience.
We took the Maid Of The Mist which gets as close to the Horseshoe Falls as it can - the last passengers to board will find it tough to get to the rails of the boat, to get the best view - my sons had to squeeze through to see anything at all over the adults, but it is a great experience (ponchos are supplied!)
My favourite experience at the Falls was standing as close as you can get to where the water actually tips over the edge of the Horseshoe Falls - it is just like being on a ride - really exhilerating! I didn't notice at first how WET I was getting!!!
However in the center close by - where you can line up to walk behind the falls - the restrooms have driers to help you dry off a little!! BTW, the line to walk behind the falls was really long when we were there and we didnot have enough time to experience this.
The Canadian side is thought to have the best views - we saw the people descending along a path next to the American Falls but I don't think they'd get much of a view of the Horseshoe Falls which are more spectacular.