Head up just north of San Antonio to Boerne and visit the Cave Without A Name and Cascade Caverns. They are both beautiful caves. You can do them both in one day and they are well worth the effort.
If you do anything outdoors during daylight hours, wear light, brimmed hats and sunscreen. There’s nothing quite like getting a wicked sunburn in the part in your hair, and on the tops of your ears (and feet if you wear shoes that expose your skin). Drink lots of water! The humidity makes you sweat a lot, and dehydration sneaks up on you. Iced tea works fine too. If you’re doing a lot of outdoor activities, you might want to plan a midday nap in your hotel room. I’ve lived in Texas my entire life, and I promise that the July and August heat is seriously brutal and draining even for natives.
I want to reiterate this point. If you go to Enchanted Rock, plan on getting there at oh dark thirty. If you get in, hike up the dome and scramble on a few rocks and then hie thee back to Fredericksburg before the sun turns the whole park into one giant frying pan. Fredericksburg is a cool place unto itself. There are lots of German things to do there as well as the Nimitz Museum.
You could try driving along the Highland Lakes chain. There are parks associated with most that you could checkout. You could end your trip at the Oasis restaurant on Lake Travis to watch the sunset. The sun doesn’t set here in the summertime till about 8:30pm so you have plenty of time.
The San Antonio Botanical Garden is nice–pretty shady in most places so maybe it wouldn’t be too hot. You can also catch an air-conditioned bus tour by the Menger Hotel/Alamo area. It takes you around the city and to all the missions. It also stops by some museums–you can hop off and catch another bus at your desire. They run every few minutes.
The Hill Country Hyatt is a comfortable place to stay and relax and is close enough to most places you’ll want to visit.
Ditto the recs for Fredericksburg, Pedernales, Highland Lakes, Oasis, the caves and caverns, Enchanted Rock, everything really. It’s all good.
I’m glad you mentioned the Hyatt Hill Country Resort! Our family vacations there regularly. It has like 5 swimming pools, at least 2 large hot tubs, and the best lazy river I’ve ever seen. It winds through a bunch of trees, has a mini sand beach, and you often can buy drinks (including alcoholic, if you wish) without even leaving the water. I’ve timed the trip around the lazy river at 15 minutes, and due to the trees, flora, and windiness, you can almost never see any other portion of the river. Most evenings they have free s’mores roastings. There are nature trails, golfing and other spa amenities. Warning: you either must have children or a high tolerance for children to get maximum enjoyment (though they do have an adults-only pool and hot tub). Oh, I should also mention that it’s right across the street from Sea World, which is always worth a visit.
I’d probably hit the San Antonio sights, then spend a day or two in Fredericksburg (hour and a half?) and Boerne(45 mins), then spend a couple of days in/around Austin- it’s about an hour away, and finish up with a day in New Braunfels either tubing on the river or at Schlitterbahn. (no sense in getting sunburnt early in your trip!)
As far as dining goes, check out some of the places to eat south of downtown, far away from the Riverwalk (which is just brimming with tourists). The Cove, La Tuna, Blue Star Brewing Company (and arts complex), The Guenther House, and many other places in the King William Historical District are all off the beaten path and are many, many times better than the expensive restaurants on the Riverwalk.
Be sure to take a tour on one of those river barges. The guide will probably point out the hospital where Carol Burnett was born. (Seriously. I was just there last month.)
Sorry for the length.
Arizona is way hotter than Texas hill country so if you did fine there, you’ll do fine here. Almost all buildings are air-conditioned so as long as you stay somewhere where you can easily get indoors/in the shade/in the water from 12-3, you’ll be alright.
Get some hiking sandals if you don’t already have some. You’ll just end up soaking through your socks and trapping loads of heat in your feet otherwise. And make damn sure the AC in the rental works.
Even though you said you don’t do waterparks, I’m thirding Schlitterbahn because it really is awesome. It’s a little more expensive than a lot of other waterparks, but cheaper than Fiesta Texas (bad the last time I went) or Sea World (merely okay but not up your alley). Most of it’s spring-fed so the water is naturally cold no matter how hot the weather is and you can bring your own food into the park so you don’t have to pay out the ass just for some midday comestibles. Plus since it’s in a fairly small town, you’re not stuck eating at Chili’s for dinner.
Tubing on the Guadalupe river is also always fun. There’s lazy parts where you can just drift and then there’s some decent rapids depending on your preference. Don’t know what the water level would be like after two months of basically no rain, however.
If you plan on going to Austin for a few days, you may want to check out Barton Creek, an icy cold spring-fed pool in Zilker Park. Downtown also has tons of great restaurants and you’ll just miss the vast majority of the idiot frat boys and sorority girls.
Enchanted Rock is nothing but a gigantic chunk of slippery pink granite so be doubly careful.
Fredericksburg is always nice. The sidewalks are mostly covered and there’s plenty of places where you can stop in and get a drink if you’re thirsty. It can get pretty crowded though and all of the stores close at 6:00 so either get started early and plan on sacking out early or have plans for something to do in the evening.
Yes, Texas is hot in August. So scheduling your outdoor activities early or late is a good idea. But the San Antonio’s humidity is a bit less than I’m used to–moving into shade actually helps. (Warning: I’m a Houstonian.) Outdoor activities involving water are good. Here are some more notes on mostly indoor stuff:
The McNay Museum is housed in a charming old mansion with a new addition built since my last visit. Its Tobin Theater Arts Gallery features this show which will, alas, be gone by your visit. The San Antonio Museum of Art is the city’s biggest museum, housed in the old Lone Star Beer Brewery. A great Antiquities collection & Latin American Art–including delightful folk art.
The Blue Star Arts Complex emphasizes contemporary stuff. Nearby is The Guenther House–great for a quick bite in a charming setting. Right across the River is The King William District–fine old German homes worth a drive-by, at least. Hey, that last link is part of Literary San Antonio; you could go back downtown to The Menger Hotel, (next door to the Alamo) where Oscar Wilde stayed when he “did” Texas. Or you can follow the River south to visit the other missions.
The Southwest School of Arts & Crafts is housed in the old Ursuline Convent. There’s usually something happening at The Guadalupe Cultural Arts Center. The Institute of Texan Cultures–located in Hemisfair Plaza–is fascinating. Gosh, who knew that Texas had a history?
TheWitte Museumis located in Brackenridge Park, along with the Zoo & TheJapanese Tea Gardens. During childhood visits, the Witte was amazingly crammed with stuff that has since filled up several of the places mentioned above; it’s been modernized but is still worthwhile. Back then, the Japanese Tea Gardens was called the Sunken Gardens–because of the recent unpleasantness.
The Riverwalk can get crowded but, for all its commercialism, is still damned charming. There’s usually an evening show at The Arneson River Theater; the one I attended was surprisingly good.
There’s lots of other stuff going on; San Antonio is a big city. And I haven’t mentioned food. Yes, the River Walk restaurants can be overpriced; check the posted menus. Have fun.
I’ll tell you what not to do: Even though it might seem like a cool idea to motor down to Laredo and maybe go across to Nuevo Laredo, DON’T DO IT!
I believe our dear doctor is with you there.
You could scoot ~85 miles down Highway 90 to Uvalde to visit the Matthew McConaughey Historic Birthplace. If that’s closed, you might try the John Nance Garner Museum (part of the University of Texas Center for American History).
En route, you’d pass through Castroville, “The Little Alsace of Texas”. You could also easily find a place to cool off in nearby Concan, home of both Garner State Park and the “best little swimming hole in Texas” along the Frio River.