I do hunters and currently am doing only local shows, but am happy to contribute what I know/saw from many of these barns. As everyone else has mentioned, your A-level shows are quite limited to Ft Worth and Houston; there’s a handful of others here and there but that’s the brunt.
For barns themselves, I wound up at a small one, as I mentioned I’m only doing the local shows but, more importantly to me, it was of the utmost importance to find somewhere with adequate turnout (and by adequate I mean over 4 hours…). Both SwitchWillo and Madrone had horrifically limited turnout. I can’t speak to Monarch if only because it was nearly impossible for me to get in touch with them.
Based on what you’re looking for, and knowing you’ll be based out of Georgetown, I would explore Still Point Farm in Granger. The commute would be quite easy and they do all the big A shows in addition to the local ones. The trainer there is super kind and they just redid their arena footing. You may also like Empire Acres, who does ALLLLL the big shows and whom I’ve heard good things about.