Drive to Austin. That is what my wife always says.
Real Ale makes some decent beers, so that recommendation is good. Any excuse to drive up to the Hill Country is a good excuse.
If you can find a place that has Live Oak on tap, try the Hefeweizen or the Pilz. Only had those in Austin, don't know if they get to San Antonio.
If you are downtown, and go to the Riverwalk, the best thing you might find is Shiner, unless things have changed in the last 5 years.
Edit: Get some Texas BBQ when you are there. Lockhart and Luling are 2 of the top town for Q, but I have had some good Q in San Antonio.