Greenery
My mental image of Texas was informed by this airtight syllogism: cowboys live in Texas; cowboys live in the desert; therefore Texas is desert. I did see some proper desert complete with cacti while driving outside Austin, but the city itself and its immediate surroundings are really shockingly green. I think this has something to do with how Austin is bisected by the Colorado River - one of the few reliable all-weather water sources in the whole southwest - so ecologically it's a literal oasis, but that's just a guess I'm not backing up with any actual research.
Grackles
All those unexpected trees are also pretty loud, because they all have at least one grackle sitting in them at all times, without exception. These are starling-like birds, a bit larger than a robin, and I cannot overstate how these guys were everywhere. Seriously, I cannot recall ever being outdoors and outside of sight or sound range of a grackle. They're also really loud, especially around dawn and dusk, with a harsh call reminiscent of a power tool.
That description might paint me as anti-grackle, but I actually love the little dudes. In an odd way it made me feel at home to be yelled at by a bunch of black trash birds. Combined with the zero crows I saw there, my hypothesis is that "little bastard bird" is an ecological niche; in Washington it's occupied by corvids, in central Texas it's by grackles.
Cool Typography
I can't think of any other American city with such a focus on fonts. Portland, OR is maybe second, but it's a distant second. In the city center there was a lot of the We-Wish-We-Were-Apple Sans and That-One-Trendy-Serif-Hinge-Uses, same as it ever was, but there's also all kinds of bespoke signage typefaces that appear hand-lettered. Some are obviously new additions that try to affect a retro aesthetic, but most I suspect are actually authentic pieces from the 60s and 70s. It's times like these I wish I had a phone with a decent camera so I could show you some examples.1
But not that much. I actually like having a terrible camera phone, but that's for another post.