I live in Austin and frequently take "stay-cations" and am familiar with all the properties. All of these are good choices. The Westin is definitely the nicest and most luxurious. They have a great rooftop pool and their restaurant Stella San Jac is very good with a great selection of local brews and a good wine and cocktail list. Rooms are modern well appointed. If you wind up on a low floor and your room faces 6th street, you might be bothered by the noise from 6th street. It is a short walk from the convention center. The Element and Aloft share the same tower. All the rooms on one half are Element and the other Aloft. I prefer The Element as it is stylish and modern. Rooms in both are fairly small though for both. The Element provides a nice free breakfast. Caroline's on the first floor and Caroline's upstairs is a solid and lively restaurant. This is the farthest from the convention center but definitely walk-able in 15 minutes or less. The Residence Inn is closest to the convention center and shares the same building with the Courtyard. There isn't anything special about this property other than there is a shared restaurant/sports bar called Champs and there is a Starbucks on property.