My Canon FD 20mm is on one of my cameras at least 95% of the time.
For landscapes, though, I find that I can typically do far better with something like a 135mm or 200mm. Far too many photographers try to use a 20mm or other wide angle to "get it all in" in a landscape shot. I find it far more effective to use a long lens to pick out and focus on some particular interesting element.
What I do often use wide lenses for, though, is the same sort of thing-accentuating scenery elements by placing them really close to the lens. This is quite effective, but requires more effort than I often want to expend
