Be advised that the Austin course is much different than it was 2 years ago. Used to be all downhill, north to south, but now you face exposition/enfield around mile 8 or 9, and a small issue with the stuff at around 24 or so ....
The word on the street is that if you want to have a good time (relative to what you could do in a marathon), your best bet is San Antonio, Dallas, or Houston....