Hi John, ... highly recommend Four Mile Creek SP. We were there last year. The sites were big, level, spaced well, and the whole grounds (including the restrooms) were clean and in good repair. Here is a link to campsite photos:
http://www.campsitephotos.com/campgr...Mile-Creek-042. The lake front sites go quickly, but the others are also very nice. Reservations can be made 9 months in advance, so if your dates are firm the sooner the better.
The windshield pass you get when you register will also give you access to the falls area because it is also a SP - free parking as often as you like. The falls area is about 15 miles away, but we didn't mind that. The area between the falls and Four Mile Creek SP is remote and there is very little traffic on Robert Moses State Parkway (about 20 minutes). We have some other places to see first, but we plan a return trip and we will stay there again.
We also recommend the Discovery Pass. The two of us thought it was a bargain, but it gets expensive for a bigger family. The in-the-park shuttle is $1 a day, runs frequently, and will get you anywhere you need to go. The NYSP windshield pass will also get you into Fort Niagara free. They have a great pool there. We went into Canada twice, and recommend that also. Watch the times you cross the border because the back-up at customs can really get long.
We don't recommend going over the falls in a barrel. We had a great time - hope you do too.
If you use the link, we had site 232. It was great being right on Lake Ontario.
We thought parking on Goat Island was the easiest to get to and the best starting point for most of the attractions.