Sorry "sk8board", but this question has nothing to do with HDR or even anything to do with digital. The asker is asking about in camera multi exposures on a single frame of film.
To answer, I like to try to combine complimentary elements with double or multi exposures, or, contrasting elements can also work good together. Such as a shot of a beautiful, clean landscape, along with an exposure of a factory belching out smoke. Or a shot of a rubber ducky with a shot of an old swing set. Or a shot of an empty beer bottle with a child's doll.
Those are not "landscape" examples, but you get the idea. Here are lots of double exposures taken on black and white Ilford film with my Holga:
http://www.lightanon.com/-/lightanon/gallery.asp?cat=92459
steve