A solid, lightweight tripod is a landscape shooters best friend. I am a big fan of Gitzo tripods. I have have two tripods, one for my 4×5 (GT2530), and the other for my 8×10 (GT5541LS). This way, I can have both cameras setup at the same time if need be. When shooting in a remote location (near my car but away from other people), I will often leave both cameras setup at the same time. That way, I can be ready for two separate shots within moments of each other.
When talking with fellow photographers, I will often hear how people have a disdain for tripods. I usually suggest that the person has never used a good one. A good tripod is one that you will actually WANT to use, even if the scene does not necessarily require it. A love/hate relation with a tripod is not productive to producing quality photos.
Sure, a tripod is meant to keep a camera steady. We all know that. However, they go on to provide an even more important role in photography. When mounted on a tripod, you now have the ability to have very precise control over your composition. I try to align certain elements with the corners, or edges of my photos. I find it very difficult to do this with digital SLRs or 35mm cameras, even though they are made to be hand held.
Beyond this, a tripod also allows me to let go of the camera, and step away from the viewfinder to view the bigger picture. Maybe there is something about the composition that I have neglected while looking through the viewfinder? I like to set up the composition, then step away from the camera and look at the scene. When I return to the viewfinder a few moments later, I will often realize a mistake I have made in my composition. I step away one more time, and see if I should change anything. If no more changes are necessary, I’m pretty sure I will not need to crop the photo in any way in the computer.
Much of my shooting is done at the beach, or the desert. Gitzo tripods do very well in these situations. Sand and water will destroy most tripods. However, a properly maintained Gitzo might just last a lifetime. They can certainly be very expensive, but they are also much less than a lot of professional grade lenses. To me, a solid, reliable tripod is just as important as a sharp lens.
A solid tripod head is equally important as a set of good legs. Expect to spend nearly as much for a head and system of QR plates as you do on the legs. My favorite head for my 4×5 setup (pictured above) is a Kirk BH-1. This is the one piece of photographic equipment that I have owned longer than anything else. For my 8×10, I use a Gitzo pan/tilt head that is solid, and not very expensive. For those who are using 35mm or digital SLR cameras, I would highly suggest purchasing a custom L bracket. These are available from both Really Right Stuff, and Kirk Enterprises.
If you budget about $1000 for a high quality tripod/ballhead setup, you will be in good shape.