Reschke,
San Antonio:
Tour the Alamo (forget what Skull says, it has a LOT of history and is very interesting), go to the River Walk for the beauty of it, eat at Shilo's for lunch (or go to Mi Tierra if you want authentic Tex Mex), and visit the Mission's around San Antone for some more history.
Austin:
Go to the Broken Spoke if you want to see a real old-time honky-tonk, Chuy's has nice food, Antone's for live music, 6th street for a selection of bars and live music, and visit SRV's statue in Zilker Park (south side of the river north of Auditorium Shores).
And, hey, if you can make it to Houston again we can get a couple of Shiner's at Wild West, I know the GM there and we could drink for free.
Cheers mate.