Let's see if I get this correct:
Faint, Very Light, Light, Fancy Light, Fancy, Fancy Intense, Fancy Vivid, Fancy Deep, Fancy Dark. 

Did I get it right?

David is going to have to attack the question in terms of price.  I do know, however, that the more PURE a hue is, yellow, for example, as opposed to brownish-yellow (yellow hue with a brown modifier), the more coveted the stone. For the record, a pure blue is almost impossible to find... most have quite a bit of grey in them, more than the other coveted colored stones (and, I'm not sure that GIA even notes much grey in the blues they see... perhaps they are so happy to have something that appears "blue" that they don't mention the grey at all!). David has/had a greyish diamond that he said appeared blue... but, GIA called it grey.  I never saw it in person, but, since most blues we see are loaded with grey, this particular stone had potential to be the deal of the decade! I don't think they've ever found a PURE red diamond.

And, I would imagine that when a diamond's hue is totally saturated color (different colors have different color saturation points), the more highly it is prized.  For example, yellow seems to reach maximum yellowness (brightness) at about Fancy Intense.  Any darker, and the color begins to look less vibrant, perhaps more orangy, brownish or greyish. So, a pure yellow diamond, with no modifying color, at Fancy Intense or Fancy Vivid, should command the highest price for yellow diamond.  After that, the various modifying colors, orange-yellow, brown-yellow, green-yellow, and etc, are most likely placed in order of desirability based upon their overall appeal, as well as yellows with not-so-much saturation (Fancy Yellow, Fancy Light Yellow).  I'm not sure which would be most desirable after the "perfect" Fancy Intense Yellow - Fancy Intense Yellow with a color modifier (green, for example, would be something like Fancy Intense Greenish Yellow) or the less saturated pure Fancy Yellow with no modifier. Yellow with a grey or brown modifier is generally less pricey. However, beauty is in the eye of the beholder, isn't it?

And, to complicate all this, different colors reach their different saturation points - or most vivid and bright hue - at different places on the GIA scale.

Does this help at all? Or, have I totally befuddled you?

Welcome to the world of colored diamonds. 

Actually that makes sense....I think the blues (or blue/grey) have higher values at deep....i think, so each color it depends, right?

T-here's a GIA Fancy Red .21ct Rad, it's so gorgeous!!!

See, I knew I was right when I did THIS: 

Hey T,
I think your perspective is extremely important- one of the things I love about this stuff is that "expert" opinions mean little if the person getting the stone does not love it.

Many people prefer an Intense to a Vivid- for exactly the reason that some people like a W-X just as much.

When I was training to be a salesman on the road, I was a driver for this French Guy....
He had some pretty funny sayings.

His definition of an Expert ( imagine a really thick French accent now)
"Ex is something that was, and spurt is a drip"

Trinkette, I can't believe you're even saying that . . .