We usually go see these places when we get out of state visitors.
Dallas has a fantastic aquarium and botanical gardens. Fort Worth's zoo is one of the best. I'm trying to think of kids stuff. There's a really neat life size bronze cattle drive in downtown Dallas.
Check out this page for the Tyler area:
http://www.texasoutside.com/explorin...ringtyler.html
Tour the Dallas Cowboys Stadium.
Waco has the Texas Rangers Museum.
Up in the Pan Handle is Palo Duro Canyon.
We hope that helps. If you need any specific info let us know and we'll try to get for you.