Catskill mountains, NY?

If Butternut Grove in Roscoe is still open you would like it. Also Pleasant Valley in Downsville is also nice. Beaverkill SP if still open is also a good choice.
I consider the area around Roscoe and Livingston Manor the Catskill's though there are many acres to visit.
I have been going there for the last nine years so I'm fairly familiar with the area.

Lake Placid KOA is good for colors. Many campsites in the fall foliage areas are going to be booked up.

There's a KOA in Saugerties and Rip Van Winkle RV Park not far from there.

KOA

Rip Van Winkle

Be very careful following the GPS in the Catskills. There are some dangerously steep grades in the area. Best to stay to the biggest roads.

Check around. Many campgrounds close on Labor Day!

I say Go another hour or two further and stay in Vermont

I stayed here a few years ago and thought it was a nice campground:

http://www.tallpinescampground-ny.com/index.html