Unfortunately for a city the size of Houston it is a little lacking on the micros and brewpubs... much like alot of other larger cities of the south, and much like where I live now down in South Florida. Luckily there are several pubs in planning, but most of the Texas breweries are around the Austin and hill country area. You can check out the brewery list at http://www.craftbeer.com/pages/get-local/find-a-us-brewery
. There are a few others around the Houston metro besides just Saint Arnold, but they are by far the most well known and biggest micro there. If you want to go to an Budweiser faciltiy there is one on the east side of the city near the I-10 - East Freeway/610 interchange, but otherwise than that, Shiner is about a 2 hr drive to get to the Spoetzl Brewery and Conroe is about 45 minutes to get to the Southern Star.
Also, besides the Flying Saucer and the G-man, if you want to browse a fairly large selection of beer, Spec's has a good selection. There are several locations around the city, but I believe the one on Smith St on the sw side of downtown is probably the original and largest store.