Justin and I are in San Antonio. The Alamo is in our downtown area and there are plenty of cafes and such you can run into if it's cold out. Not to mention the Alamo itself is treated as a shrine ("Shrine to Texas Liberty"), so when you're inside it you are in pleasant, climate controlled comfort year-round. While there you can also visit our Riverwalk, which is beautiful year-round and alight with Christmas lights from early December through each New Year's Day. We also drain the river once a year for cleaning... as it's really a concrete channel that directs part of the San Antonio River (a real river) into our downtown area. I can't remember when it's drained yearly--after St. Patrick's Day, I think. We've been known to dye it green but most years it doesn't need help turning green itself ;-) You can take a river boat barge ride down the river or eat on one of the Riverwalk cafes. Also some historic hotels along the river, though they're too expensive for most of us locals {grin}.
The Tower of the Americas reopened and is fully renovated with a wonderful new restaurant, with the unique feature that it rotates so as you dine you get a 360 degree view of the San Antonio "skyline" (such as it is... it's a nice view, nonetheless.) We celebrated my birthday year before last up there.
Our time is limited as well so we miss out on prime camping weather, which really is right about NOW here in San Antonio. It's already been 84 or more here on a couple days in the past couple weeks. It's beautiful and sunny today and we won't see 90 degrees for several more weeks, if we're lucky. We have had a 100 degree February before, however. Not fun.
Camping in summer is still when we end up doing most of our trips due to work schedules and such. We try to take off midweek and hit parks when they're not (quite) as busy. And we plan our days around the heat so we can enjoy the trails and parks and still be in shade or sipping a cold beverage back at camp when the heat's at its worst.
For wildflowers, check the Texas Wildflower Watch ->
Texas Department Of Transportation Wildflower Report
They're generally best viewed on major highways throughout South and Central Texas (including the Hill Country) where the Texas Department of Transportation seeds periodically ->
Wildflower Program
You can also visit the Lady Bird Johnson Wildflower Center in Austin year-round (though most strikingly beautiful in spring, not surprisingly) to see our native flowers ->
Lady Bird Johnson Wildflower Center - The University of Texas at Austin