Hey Charles,
All good things to do posted above and check them out. Austin is a very different place than it was 20 years ago. Traffic was always bad, but is 100X worse now. There are a lot of homeless panhandlers, and beggars there; particularly in downtown area. Which is a shame cause used to be a lot of cool things to do downtown if one had the time.
If you are in the Austin area (and especially making a trip to Fredericksburg), then there are some places you may want to see or eat at. This time of year, the Congress Avenue Bridge bats emerge every night over the river; I think its about 1-2 million that live there and come out every evening in the summer.
Just SW of Austin is a little place called Driftwood that has the original Saltlick BBQ joint. It is stupidly overpriced, but I've never been there when it was not very good and the atmosphere is pretty unique. If you are heading to FBurg from Austin, then your best bet IMO is to avoid west Austin and Dripping Springs at all cost unless it is at 3 AM in the morning. A better route may be to travel down to San Marcos and head to Blanco, then Johnson City, and on to Fburg. May be longer, but more than likely less traffic and delays if during a weekday. There's just no backroads to get there anymore.
If you are into freshwater and Indian artifacts/archaeology, might be a good idea to stop by Aquamarina Springs in San Marcos. The University owns it now and they have glass bottom boat rides on chrystal clear river that is probably the oldest inhabited place in Texas. They've found all kinds of megafuana and Clovis culture stuff there if you are interested in that kind of thing. On your way to Fburg from Johnson City, you can veer south and go check out Luckenbach and have a beer or an iced tea; might be some bikers there, but they good people. If you have the time, and into the outdoors, be cool to take a FM Road north from FBurg and head to Enchanted Rock. Its a giant exposed granite rock and is just cool to see with lots of interesting places to hike and see. I know its a a small chain restaurant, but the Mammacita's in Fburg is very good Mexican food if you like Mexican food, but there is plenty of Great German food, wine and beer there as well. Chancey