Here's where I'd go (and yes it's a long list). Many of these would be great retirement options if you don't need a retirement community (like Del Webb). Personally, I'd live in the Hill Country and travel into SA, when I needed. Obviously that's a personal choice
Austin - 6th Street etc. if you want 'bigger' city nightlife/music.
New Braunfels - Nice German town.
Fredericksburg & Enchanted Rock. Wonderful, but expensive town. Wish we had my grandmother's house to sell all over again.
LBJ Ranch - I don't care what your politics are, I found the tour to be quite interesting.
Wimberley - Another nice small town. I know a few retirees here.
Kerrville - A bit bigger town, but again nice. More shopping etc. than the smaller towns.
Comfort - Closer to SA, nice place.
Boerne - Cowboy capital of Texas or something like that. Again - closer to SA.
Wineries throughout the region, if that's your thing.
I'd do a two day road trip out of SA. Boerne, Comfort, then spend the night in Fredericksburg or Kerrville. Then LBJ Ranch, Wimberley, maybe Austin and back to SA.
I'd stay off of Interstate 35 between Dallas and San Antonio. It's just awful with congestion. A side road that takes longer is easier on the nerves.
Enjoy - Wish I was going.