I've never been to Austin but I'm sure it's a nice city and could do a good job hosting a Final Four. But San Antonio in 2004 was my favorite Final Four city. I liked that you could walk everywhere. There were also enough hotels downtown to accommodate everyone. A friend of mine already made a reservation for the Final Four in 2025.
The River Walk was a perfect place for all the fans and media to hang out. Just big enough to fit everyone with plenty of restaurants and bars. But small and intimate enough so you got to see lots of people - media, other teams' fans, former players, etc. I hate the Final Fours in Houston, Dallas and Glendale. Everything is just too spread out with no central place and you can't walk everywhere.