Getting UHF at 80+ miles can be done, but it's going to be tough. VHF is easier. I'm not sure if any of the Houston stations are broadcasting digital VHF stations, though.
For VHF-Hi (channels 7-13), I'd recommend a Winegard YA-1713 antenna. It's inexpensive, yet pulls in channel 12 which is over 80 miles from my house.
For UHF, you may need to gang together two 8-bay antennas. Instructions on how to do this can be found here:
http://www.hdtvprimer.com/ANTENNAS/16bay.html
A good, low-noise preamp is also essential. I'd recommend a Channel Master 7777. It also has a built-in FM trap which you may need.
Height will help. But at 80 miles, you'll need a
lot of height to see much improvement. If you can get an antenna 50 feet up, go for it, but don't fret about one or two feet. (Try going to tvfool.com and playing "what-if" with the antenna height.)
Reception is probably going to be spotty no matter what you do. But it will generally be best after dark. During the day, a layer of warm air forms near the ground which can refract TV signals upward, preventing them from diffracting around hills and other obstructions. (This is like the "mirage effect" you see sometimes when driving on the highway during a warm day.)