I finally left Austin and headed towards San Antonio, where I had found a place to stay through couchsurfing.org. I arrived pretty late and had a low-key night hanging out with Chris (my cs host) and his friend Russell.
San Antonio was hot. I went downtown to see The Alamo monument and it was so hot walking around outside that afterwards I found an air conditioned cafe and sat there drinking fluids for an hour. The Alamo:

The Alamo is an old fort that was over-taken by the Mexican army prior to the Mexican-American war. I don't know all the specifics but the rallying cry 'Remember the Alamo!' more or less plunged the United States into war with Mexico. Davy Crockett and other mythical old-time American heroes died at the Alamo. It was hot and it was crowded. I wasn't all that impressed; I think it's mostly a Texas thing. There was a big monument out front.

The rest of San Antonio was pretty neat. The Riverwalk district is nice - there are lots of interesting shops and resteraunts surrounding it. It was too hot during the day but I returned one evening to walk along the river. River taxis went up and down and it was very pleasant.
The Tower of the Americas reminded me a lot of Seattle's Space Needle.
The heat burnt me out of seeing many San Antonio attractions - each day it was over 100 degrees Fahrenheit well into the evening. I mainly hung out at cafes and the magnificent downtown library. On my third evening in town I met up with my friend Steve (who I had met up with in Austin the week before). We had dinner and a couple drinks. Steve is a cool guy - I love hanging out with him. He's got a really interesting perspective, he's in the top 5% of his class at the Baylor School of Law, and he likes to backpack alone into the wilderness and live off the land for several days at a time. I'm sure we'll have some adventures in the future.