I recently bought a Gitzo 2930 Tripod. It is part of their Basalt line, which is between Aluminum and Carbon Fiber. I couldn't justify the cost difference for a Carbon Fiber tripod but I wanted a light tripod that would be with me for years.
So far, I've been very pleased with the results. I carried it down into the Grand Canyon on my recent hike for some self portraits and bracketed shots for HDR.
I really like the build quality and locking mechanism for the legs (the kind you twist, but they work and require only about 1/2 turn). I can setup the tripod in seconds and it has been stable for everything I need.
This model does come with a center column to extend up, which I recently used to get a picture from an angle I could not have otherwise achieved. I had the camera up above my head angled down, and used live view to compose the shot. The hook to attach a weight/bag really came in handy when I did this. I was really surprised at how much additional stability it provided.