Here's my $.02
Round vs Square - Round is a little more old school, but still in style. Square has become the craze in the last 15 years. I used to cringe at square toe, now I have three pairs. Just don't get a damn pointed toe. They are old school AND out of style.
Material - All personal preference and how splashy you want to be. I personally have leather, ostrich, and lizard. Leather are every day and the other two are for special occasions. Ostrich is kind of delicate with leather being more durable. Lizard are in-between. I don't have the money for caiman or alligator, but those are pretty durable.
Sole - leather can be slick as snot (you can bust your butt on the wrong surface), not as durable, but can be easily resoled. You can also feel more of what you step on with leather (rocks). They are great for two stepping. Rubber soles last much longer, but don't slide as well for dancing.
Heel - Go with a walking heel (shorter). Riding heels are for...well...riding. Walking heels are much more comfortable.
Fit - look for a little room to slip in the heel (not a ton though), and it should feel like a firm handshake around the front ball area of your foot. ( The widest part.) They will stretch and loosen a little around the ball as you wear them, but if it's painful they won't stretch that much. If it's painful go to a EE width. I currently wear a 13 in running shoe and a 12D in cowboy boots, and I have found they can fit slightly differently from pair to pair even from the same brand. No crazy differences though.
Care - Just like any good boot they can last a long time if you take care of them. I use Bick 4 leather conditioner on all my boots, even my exotics. I used to polish my boots a lot, but now I just use this regularly.
Also, if you wear them a lot invest in a boot jack. Those things are money! Good luck, and let me know if I can help with anything else. I hope you have a great time in Texas.
Edit: If you get your tux/suit tailored make sure the pant length is for boots. Most are tailored too short to wear with boots.
In fact, there are 3 pairs in reserve besides my newer Noconas. Goat, python, lizard, elephant, I've gone through a lot! Buy what looks good to you, that you think will get some more use than just one time.
