In general, people are a distraction in a landscape. With practice you can become skilled at "getting rid" of people (and I don't mean running at them screaming "leprosy, unclean!!!"). Wait until they step behind a tree, reposition yourself slightly, etc. It takes some thought and practice, but the results are well worth it.
That being said, a single person caught unawares in a particular location or physical attitude can really add to the composition. But these situations are really pretty rare. What a happy day it will be when that ridiculous photo class aphorism of "always include a person in your photographs" is put to rest. Anyone who can't compose a shot without sticking a person in it needs to get another hobby!