how far is it from Houston to Austin, as I know I can get there in a little under 3 hours.

Having made the drive from Houston to Austin a few times, I'd say it's about the same. It's a tad quicker to get to SA from Houston, but only by about 30 min. Personally, Austin is great for me, as I live north of SA and could probably make it there in 45 min driving at an easy pace. (The added bonus of Austin is that I can drop my wife in San Marcos on the way up so she can spend the day shopping, thereby making this something she'd support without question )