Stone Werks has pretty good ones. On the half shell are always fresh and its hard to beat the Rockefeller hands down. I can vouch for the 1604 and Blanco location. I don't frequent the other ones.
Appreciate the plug. My family owned business supplies pretty much all the restaurants listed in the thread. Ask for Rick Groomer (my dad) and tell him your an ag from texags and he'll make sure they take care of you.
By far the best oysters I've had in town were at the Sandbar. They import them from British Colombia and the east coast. You pay a pretty penny for them though. $3 an oyster to be exact. I typically go to Stonewerks or Luke for gulf oysters and they are great. Although, sounds like I need to go get them from the source at Groomers and save some money.
[This message has been edited by hudson2508 (edited 1/29/2013 9:14a).]