If your objective is to produce an image that closely approximates the
perspective of the human eye, then the normal 50mm lens is invaluable.  It
imposes very little graphic control on the subject, and I use it more than
any other lens.

An 80-320 is entirely in the telephoto range.  I personally don't shoot
landscapes with telephotos, because I do not want compression of the objects
in the photo.  Clearly, I am trying to achieve a particular effect--that of
a "true" sense of perspective, but you may have another goal in mind.

If you can get your hands on Brian Bower's book, "Lens, Light and
Landscape," he has numerous examples of how landscapes look when
photographed with different focal length lenses.  He will have, for example,
4 different shots, each taken from the same spot, but with different focal
lengths.  You can see the dramatic impact that different focal lengths have
on the final image.

For me, the normal lens records the scene as I see it, and that is what I
want.  The normal lens is also typically the sharpest and fastest lens
within the manufacturer's range.  It is also relatively inexpensive and has
the least amount of distortion.  Not a bad combination of speed,
low-distortion and low price.