East Texas, more Southern than Western, is home to both "downhome" cooking and "soul food." For the former, more prevalent in the northern sections of East Texas, look for dishes like fried catfish and vinegar pie. Soul food occurs more often in the southeast of Texas and you'll find Cajun and Creole dishes like gumbo alongside such classics as candied sweet potatoes.
Cajun cuisine slips into most Beaumont menus; especially when it's intermingled with downhome cooking and barbecue. Creole is another popular flavor here. Expect some dishes to come with French names and if you're in the mood to have (or try) frog legs, crawfish, or barbecued crab with your gumbo, this is the place. But Beaumont has enough restaurants (including ubiquitous chains like Chili's and Fuddruckers) to satisfy everyone. Steak is here in quantity, sometimes, mind, cooked Cajun style.
Some areas of Texas are centered in steak, others in Tex-Mex, others in Southwestern cuisine. Corpus Christi is about seafood. Most restaurants will have some kind of seafood dish included on their menu. You, yourself, can go catch a fish or go crabbing and have a restaurant cook it for you, or you can buy fresh shrimp and fish right at the port. As one might expect, then, restaurant seafood served tends to be caught from the bay rather than imported. It's also often cooked Cajun style. Oriental and Mexican restaurants also have a strong presence.
Seafood is the big food "genre" in South Padre Island and Galveston Island, with seafood being the dominant one by a long stretch. Like much of Texan coastal food, the seafood in Galveston can have a distinctly Cajun flavor.