Please note that the Westin Galleria Hotel has a different address from the Houston Galleria Mall. The mall complex is quite large and sits between Westheimer and West Alabama (west of Loop 610) in the Uptown area of Houston.
The hotel is built into the mall. The main entrance of the hotel can be accessed directly off West Alabama Street (note this is a one-way street, and it is eastbound). There is a small pull-through driveway right outside the front doors. The Galleria Mall has numerous parking garages that are free and open to the public. The hotel will advise you on where to park (but parking is free!).
There is a second hotel in the Galleria (the Westin Oaks). It is separate from the Westin Galleria Hotel. We are NOT staying at the Westin Oaks 
Westin Galleria Houston
5060 West Alabama
Houston, Texas 77056
Phone: 713-960-8100
www.starwoodhotels.com/westin/property/overview/index.html?propertyID=1053
The Galleria Mall is the fourth largest mall in the US. It houses more than 375 businesses (stores, restaurants, and even an ice skating rink). Most importantly, it’s home to the Houston LEGO Store!
Houston Galleria Mall
5085 Westheimer Rd., Suite 4850
Houston, Texas 77056
Phone: 713-966-3500
www.simon.com/mall/?id=805
Houston has two major airports. George Bush Intercontinental (IAH) is in northeastern Houston and is approximately 27 miles from the Galleria. William P. Hobby (HOU) is in south Houston and is approximately 17 miles from the Galleria.