I hardly ever go any more as I've been out of the hobby for the last 3 years - just starting again.
I like City Pets a lot. They are a full service store and they give you a better price if you're a regular customer - good place for salt and supplies in a pinch. Donny is the guy to talk to there.
I used to make the rounds: Aquarium World - Dave knows his stuff - the girls, not so much, Aquatic World on Jones, cool coral specimens (no salt now?).
My favorite was a place up the road from City Pets on Bellaire near Bissonett, I think. That store had the best corals and healthiest stock and was the best place to get stuff like chaeto and a handful of good sand. I really liked the owner and that he was up on newer stuff- I hope he's still there. I also had a good relationship with the guy with the store on 249 near Bammel N Houston. But I think he got a real job and his wife runs the store now or something like that.
If I'm going to buy a fish, I usually buy from Aquarium World or B&B's. I got two cyanided angels from a place up on 242.
Anyway, I'm not up on it anymore. What places do you like?