Dick_B wrote:
I can think of Cedar Point the roller coaster capital of the world; probably good for an entire day. www.cedarpoint.com
If you do spend a day at Cedar Point, I would suggest giving strong thought to staying at their campground (Lighthouse Point), particularly with the younger children. The ability to walk "home" for lunch or a nap or whatever should not be underestimated.
Knoebels in Elysburg, PA is another amusement park that has a campground right adjacent to the park. Their campground itself is unexceptional--it's clean and decently kept up, but otherwise quite plain with mostly smallish sites, some quite cramped--but the location at the park makes up for that in spades. Knoebels itself is smaller than Cedar Point, rather more traditional in general ambiance, and absolutely great family fun...and as it's run on the pay as you go system, it's quite possible to have a fine day comparatively inexpensively.