I just spent about 3 months in Houston. I stayed at the Hilton, the Courtyard, and the Residence Inn. All are downtown. The address to the Residence Inn is 904 Dallas. The Courtyard is next door. The Hilton is closer to the George R. Brown Convention Center. The cheapest rate I got was during my stay at the Residence Inn. 79 bucks. But there were times when it got higher. 150 bucks. I recommend asking for a cheaper rate no matter what they offer. I recommend that for any hotel in general. Rental cars too. Plane tickets.
If you decide to go with the Residence Inn, tell them I sent you and that I said hi. It may not get you a better rate but there’s a chance you can get a better room. Ask for something like room 318.
If you need any other recommendations let me know. Downtown Houston is pretty much a ghost town late, but it’s cool to walk around. Not much on resturants. Interesting photo opportunities though.