I took CS in Houston and flew into IAH. I stayed at the Wyndham Greenspoint, which does give a discount to people who are there for the exam. It is a very short taxi ride to the center from the Hotel. I think that the driver charged me something like $5.00 for the trip and all of the taxi drivers seem to know exactly where the center is.
A lot of people stayed at the Sofitel, which is directly across the street from the center.