If she is wanted mainly to "demo" as you say, I would definately check out at all the ideas given. Austin has some good demo shops, but nothing I would really travel from Abilene for, considering cost/return ratio. I think she is pretty darn close to Harvy's shop, compared to here. She really could not go wrong with Indian Trail.
If she ever decides to go on a spending spree, this is where I would go in Austin:
http://www.cedarcreekrecording.com/The Dixie Chicks did the "Home" album there. I have recorded there and it is very nice. They have a historic Neve desk, a great 2" machine, or can go to Nuendo (tragedy!). They have a very nice Klauss Heyne U67. The room is pretty decent. Nice folks, tons of great musicians available.
If I had a little more money and didnt mind the travel, I would go here and stay a week or so:
http://www.sonicranch.com/I did an album here and it is really one of the best kept secrets in Texas. The rooms sound amazing, and the gear list is just
insane! The musicians in the area turned out to be quite good. The lodgings and countryside vibe is spectacular. Tony, the owner, is a great guy.
Either place would be the kind of place I would want to do a finished album and lay down heavy time and cash. They are not places I would recommend to work out ideas or initial demos on a limited budget--one can VERY quickly rack up the tab at either shack.
Also, I wouldn't work at either place without a competent producer (I use myself though, heheh, not sure how sane I am!) to really take advantage of the great gear and spaces.
It can get messy hiring musicians if she doesn't have some experience with it. Both studios have good connections at getting a variety of folk, though Cedar Creek obviously has access to a dazzling array of players here.
Both shops get into about the $1k a day range, with Cedar Creek being a little less than Sonic Ranch. However, those numbers are variable depending on how big the overall project is, as usual.
KT