El Tiempo (Washington St) {somewhat north west side of Hou} offers up excellent Tex-Mex and great Margaritas. Same goes for Molinas Cantina (same area) La Groceria on Washington St is GREAT for Sunday brunch (Mexican) or any other time as well. The Barbacoa tacos are killer.
Steaks-seafood: Pappas (any) or Perry's Steakhouse...which has a double cut pork rib chop that is to die for.
Oddly enough, there's not much really, really good BBQ in Houston but Goode & Co is ok as is Luling's City Market near Galleria.
If you drive by a Whattaburger, stop and grab a few

And wash it all down with plenty of Shiner Bock
