Golf, Fish and Eat...Those are the best suggestions. Houston has a huge variety of cuisine, much of it world-class.

The golf courses are also good and plentiful. The Golf Club of Houston is where they play the Shell Open for example. You'll want to go early enough in the morning so you are done before 10:00am or the heat will get stifling.

Deep Sea fishing is an experience, and would certainly fit with a guys trip. If you don't want to go that far, you can still fish off the jetty's in Galveston and have a good time. Outdoor adventure is all going to be Ocean related - for example http://tpwd.texas.gov/fishboat/boat/paddlingtrails/coastal/christmas_bay/

The city is very cosmopolitan and enormous in size...you can find pretty much whatever you want to do here, unless your only idea of fun is hiking in mountains (never understood this...). It is not a tourist-friendly city as it is business first here and the heat keeps people inside a good portion of the year. That being said, whatever you decide to do, you should be able to find it in Houston.