@bap FYI, the steps to the North Sulphur River at Ladonia are very, very crude. They vary in size, but most being about 2.5-3 feet high concrete blocks going down about 30+ feet. Short people, like me, and kids will have to hoist themselves up onto several of them. DD was able to negotiate them at 5 yrs. Also, take rubber boots, clean clothes, water for washing up and old towels...it is always very, very, very muddy.
If you have little bitty kids, Mineral Wells is perfect. It is an old quarry, easy in and easy out. Lots of little fossils. Gets hot as heck down in there, though.
Also, there are dino foot tracks in Glen Rose. That's pretty cool to see. Don't go after a rain because the tracks will be under water.