for Mexican food, try El Tiempo. I always go to the location on Washington ave near I-10 inside the loop. Their locations are in the city and are a bit of a drive. El Tiempo is my all around favorite Mexican restaurant anywhere, not just in Houston.
http://www.eltiempocantina.com/
But there should be a Papasitos closer and they are pretty good. Emphasis is more on grilled and carne asada than true Tex Mex. If you want true Tex Mex, the place to go to is Lopez in SW Houston. By true tex mex, I am talking old school cheese enchiladas in chili gravy. Awesome!!
http://www.vivalopez.com/
Killens steakhouse and BBQ restaurants are both in Pearland, which is not terribly far from where you will be. Reservations are recommended.
http://www.killenssteakhouse.com/
An interesting place close to you that I love is T-Bone Toms. It is a bit of a dive. Nothing fancy. Home cooking, great chicken fried steaks. They have a killer appetizer, Armadillo eggs, which is brisket stuffed into a jalepeno and fried. Really good. They have BBQ, but I really cannot vouch for it. Most people eat the home cooked items there like Chicken Fried Steak and such. This place was featured on Diners, Drive Ins and Dives a couple years ago.
http://www.tbonetoms.com/
Another place that is pretty close is Gilhooleys in San Leon. Very good grilled oysters. Very cool place, but it is a bit of a dive and San Leon is a bit of a rough place. Kids not welcome though. Don't believe they accept credit cards either. If I was staying in the area you will be in, I would personally make it a point to go to Gilhooleys. Unless you do not like oysters, then skip.
http://www.travelchannel.com/shows/bizarre-foods/video/gilhooley-s-oyster-bar