J.,
I've never stayed there but have always wanted to spend the night/weekend at the Driskill Hotel in Austin. See their website and you'll see why I was impressed - www.driskillhotel.com. Last time we were in Austin, we were with our son to see Thomas the Train (and not wanting to "waste" a good hotel on a kid weekend!), and as we walked past the Driskill, we stepped inside the lovely lobby just to see what it looked like. It's pricey, but fabulous!
Be sure to make The Oasis on Lake Travis part of your weekend, as long as the weather is nice. It's on the outskirts of town, and it is a huge place where they mass produce the food - but the scenery (don't miss sunset!) is wonderful and if you can end up in a quiet enough table, it is VERY romantic. The night we were there they had a great band and the breeze was cool and it was just about as perfect as it gets for me - but my needs are pretty simple!
If you are even remotely interested, I'll recommend a trip to the state capitol. It is gorgeous. The grounds are also beautiful. I hadn't been there in several years and had forgotten what a spectacular building it is. You can do a quick stroll or delve more into the history of Texas and all the other historical stuff, but even if you just take a walk around the building and just take in the grandeur of the building and the grounds, I think you'll be glad you did. (Sorry...I think I must be a travel agent wannabe!)
Have a great trip - Austin is such a nice place.
J. M.