We stayed at this campground for a weekend last summer.http://www.koa.com/where/NY/32127.htm
We didn't use the pool, but saw other people in it. The sites were pretty good; grassy, very level, average width, mostly pull-through. Reservations are a good idea. It is a short drive to the falls around 10 - 15 miles. It is very close to the Whirlpool jetboats (that's what we were there for) and there is a bridge to cross over to the Canadian side fairly close.