Houston would be fun they have museums, live music, parks and recreation for the kids and theres Galveston,Tx thats not too far south.
I do know about Galveston and they have the railroad museum, shopping and Victoriana on the Strand, trolley to the ocean side. Rent a bicycle or skates and cruise along the 10 mile seawall.
Visit one of the county beaches or take your car and drive out to a deserted beach.
If you like old houses, see the Bishop's Palace and Moody Mansion.
Moody Gardens has a 3D IMAX, a white sand beach, an indoor rainforest and beautiful landscaping.
Good restaurants are all over Galveston, including Mexican and Italian, but seafood is the main attraction. Gaido's seafood restaurant on Seawall is very popular with the locals.
Take the free ferry to and from Bolivar (bring crackers to feed the seagulls), and with luck, you might see some dolphins. So theres a lot of family oriented events and sites to check out in Galveston.
So have fun and have a safe trip!