Depending on the timing, you might catch the Battle of the Alamo reenactment.
And while in the Valley, you can U-lock yourself to a 'dozer at the National Butterfly Center.
Best dinner I had in a long time was Odd Duck in Austin. Sunday night so all the small plates were half price. We tried everything. It was glorious
Padre Island is close by McAllen and Brownsville. Stay away from the tourist area and it’s a very nice seashore.
If you’re there in March, the line at the Port Aransas ferry is likely to be a lot longer than just a mile due to the spring breakers. The Rio Grande valley, especially Port Isabel, is also likely to be extremely busy with spring breakers. As far as Rockport goes, my recommendation for dining is the Moondog eatery. Great seafood and a great view of the bay.
The place I’d want to see if I was in the Austin area is the Hamilton Pool Preserve.
Just poking in to say “thank you” for this!
OP if you’re near Austin in spring (say Febr. thru April) the Wildflower Center is a lovely place to wander. Depending on which week you’ll see bluebonnets, Indian blankets and paintbrushes, etc.
Not to hijack the thread too much, but since Texas was settled relatively late, and there were a lot of immigrants directly from Europe, there are quite a few German settlement areas in Central Texas that retain some of their original character. There is/was even a unique dialect of German spoken by people who lived there. Fredericksburg, Schulenburg, Boerne and New Braunfels are the big German towns that come to mind, although there are a lot of other smaller ones.
There are also a lot of Czech settlements as well- Ennis, West(fertilizer explosion a while back), Caldwell, Hallettsville and Snook are heavily Czech towns that come to mind.
Here’s a map of the different settlement areas.
Check the dates for SXSW. You can’t find a hotel room in Austin then.
I’ve been to the Hornsby Bend Observatory
https://www.hornsbybend.org/
I was underwhelmed. But there were wood asps and I live in dire fear of wood asps.
If you’re into craft (farmhouse/wild) beers, make sure you hit up Jester King in Austin! It’s my favorite place out there.
Lockhart, which is between Austin and San Antonio, is widely considered to have the best barbecue in the world.