14mm, 20mm, 28mm what are these good for?

[20dnut]

I have a Tokina 28-80 f/2.8. I was looking for a prime, specifically at the 50mm f/1.8. After reading some responses though, perhaps it would be better to get a prime at the lower end of the spectrum that the Tokina gives me (28 or less).:confused:
I can figure out what a zoom telephoto 70-200 is for, but what is the advantage of a 14mm or 20mm, are they good for portraits? Would a prime 28mm with a f/ 2.8 be that much better than what my Tokina gives me? Does anyone have any samples of what a 14 mm or 20mm can do? Thanks.:)

[CyberDyneSystems]

Archetectur, landscapes etc.. these are what wides tend to fet used for the most,..

There are exceptions, but Portrait is not usually a good thing with very wide lenses as the perspective and distortion don't tend to be flattering.

Taken with a 17-40mm .. I think at 17mm?
http://cyberdynesystemsimaging.fotopic.net/p4402368.html