One thing that we have in Texas that they don't have a lot up north in my experience is Mexican restaurants that cater specifically to Mexican-Americans. I'm not trying to start a debate over what is and isn't "authentic" Mexican food because I don't think that particularly matters, but I do think it's an interesting experience to go to a Mexican food place that doesn't worry about marketing itself to non-hispanic people.
Raspas El Payasito on Coulter in Bryan is one such place that I really like. It's not the fanciest restaurant in the world to be sure, but they make the best tortas in B/CS and everyone I've ever taken there has really liked whatever they ordered. But, depending on who's working that night, it might be helpful if someone in your group spoke some Spanish. Either that or don't try to make any substitutions on your order.
Anyway, I think that's a unique experience for most folks. Tex-Mex is awesome, but it's not that hard to find in other parts of the country.