Take a look at this thread-- Suggestions Niagara Falls
Several of us here on FRF have stayed at Four Mile Creek NY state park.
It's close, cheap and easy access to the Canadian side.
Also if you are any sort of hikers at all you should consider the NY side
of the river. There is a trail that takes you right up the river nearly at
water level past the rapids and all the way to within sight of the rainbow
Also Four mile creek is just up the road from the power station that has a
wonderful visitor center where they have models and displays that show how
they shut off the water at night and channel it to generate power.
Really a great stop for a couple hours.