I not real sure where your interests lie, but there is an intriguing trifecta of State Parks up in NW Oklahoma that are known as Little Sahara, Alabaster Caverns, and Boiling Springs. There's not too much else around (it is NW Oklahoma, after all), but it might make a cool outing for the kids.

Anyway, here's the Oklahoma State Parks website with a seachable region map if that's not what you were looking for...

Oklahoma Parks, Resorts & Golf - Region Map



Oh, yeah... on the flip side of the coin, Tulsa is still under two hours away, as well.