What would you recommend for a guidebook for Austria or is Austria in a different RS guidebook?
Rick covers part of Austria in his Vienna, Salzburg & Tirol guide: https://store.ricksteves.com/shop/p/vienna-guidebook
If you go to that link and click on "What's Included," you'll see exactly which parts of Austria he discusses in the book.
If you are going to other places in the country, you will need another guide. Of course, even if you are going only to places Rick covers, I feel it's always a good idea to look at multiple guidebooks, to get different points of view.
For a more systematical overview of the country I'd recommend Michelin's Green Guide Austria.
Our local library has many brands of guidebooks--why not see if yours does and check out a few. That will give you an overview of the styles, layouts, and how they mesh with your travel style and needs.
Personally, I like to plan with a combo of Rick Steves books for lists and practical info and DK books for all the pictures, drawings, and other ways to "see" what we're planning for.
I like the TimeOut and Eyewitness guides.