The Houston area is home to many great stores, some classed as home improvement, some just have some "great stuff".
It goes without saying that Home Depot and Lowes are the starting place for most home improvement projects. Price and readily available materials make these the place to go. Sometime take an hour or so and walk the store looking at all the merchandise. Knowing what is at the neighborhood store can save time when searching for products.
What to do when something special is needed? Try Buffalo Hardware/Ace Hardware. The local Ace hardware usually carries older fittings that sometimes can't be found at the home improvement stores.
Bering Hardware is not your daddy's hardware store. This store will take a good hour or two on the first visit--fine china, crystal, specialty coffees, and, oh yes, many hard to find hardware items.
For plumbing needs check with Ferguson Plumbing, located all over the Houston area.
Make friends with these folks. They can be a great help in all home improvement projects.