I visited three of the four lounges in Houston’s terminal D. There’s the airport’s own Executive Lounge which I will cover in this post and is used by Emirates and also Lufthansa among others. There’s also a KLM lounge and an Air France lounge separately (odd, since they’re jointly owned and mere gates apart). And there’s a British Airways lounge that I didn’t have access to on this trip.
In a few months the terminal will be getting an American Express Centurion lounge. And the terminal itself is slated for replacement so lounge options will change entirely in a few years. Of course the terminal is connected airside to the other terminals in Houston, so for instance you can visit United Clubs as well.