If you do Inks Lake SP you also might consider at outing to Longhorn Caverns SP right near by, its a cave tour that is interesting.The caves were formed into the limestone via rain and underground streams. Large deposits of calcite left some interesting features. Fossils date back to native americans and even the civil war later
Longhorn Cavern State Park
There were at one time 21 state parks alone in the hill country some are now run by the city or county. So you have lots to choose from