San Antonio is so much fun. You can do the boat cruise on the Riverwalk, Ripley's Believe It or Not, zoo, Market Square (El Mercado). If you have time to make a little bit of a drive (about 45 minutes), you can go to Natural Bridge Caverns and wildlife park or a little bit further and go to Schlitterbahn in New Braunfels. Fiesta Texas (a Six Flags park) is in San Antonio as well.