Janerene's post is great! She suggested most all the things I would suggest
... I live 8 mi from Natural Bridge Caverns, which has nice picnic grounds
and a sluice for children to "pan for gold and jewels" (warm weather).
Next door to NBC is the Wildlife Animal Park, not to be confused with the
Riverwalk on Saturday nights. (just kidding) ))
Right on up I-35 another 11 miles is New Braunfels, a cool little Germanic
community with a wonderful old park. The Comal River springs from the
hillsides in the park, and were central to Native American livelihood,
then a mission, then the German settlers.
And Schlitterbahn is in New Braunfels! The largest private waterpark in
the U.S.- great fun. And if that's too tame, tubing on the whitewater of
the Guadalupe River (or the gentler Comal) is in the same area.
There's WAY too much to do in just one long weekend ... I didn't even
mention the Coast.
Come and fall in love, like we did. San Antonio is not a beautiful city
at first glance ... you have to experience the Riverwalk, the old parks,
and the Hill Country and the wonderful people to become a believer.
Ya'll come!