What part of Houston will you be in and when will you be here? Houston Hardwoods is northwest off 290. http://www.houstonhardwoods.com/
There is another new place close to it that I've heard of but not been to yet. Can't remember the name. There is also a Harbor Freight off 290 and Jones Road not too far from here.
Rockler is on 59, near downtown and there are 2 Wood Crafts, one on the north side and one SW on Beltway 8 (Sam Houston Toll Road) just south of 59.
I thought you were going to ask where to go and see, not for for wood. You'd probably find the same thing that you'll find in your own stores in your own town, unless you live too far from any decent woodworking stores.
Clarks Lunber Co. is one of the best ploaces for wood in Houston. You would have to look the address up and put it in your gps. Our weood turnig club met there a couple of time a year and that was the only way I could find it.