Not from SA but Austin (just up the road)
In SA
The Witte museum and it has a fun childrens science center in it,
The Alamo and Mission district
Six flags
River tubing or just up the road in New Braunfels is Schiltterbahn, the worlds best water park.
The Riverwalk and boats that go up and down it
SA Zoo
Outside of SA is a Safari tour, Snake farm, Fredricksburg and on the way to it is LBJ home
In Austin is a bunch of things, the Bullock musuem, the LBJ presidential library, the UT library-has a whole section on movie things from Al Pacino-I believe
The list could go on and on....have fun in TX