If your dealer doesn't have a vehicle with GCM paint in stock, try searching other Chrysler dealers near you. I had to drive 40 miles to find one so I could see it in person (on a Dart). GCM paint is pretty popular on the new Durango, probably because that's the color featured in most advertisements for the '14 Durango, so it really sticks with people. But since you're debating between colors (and before dropping $40K-$50K) I would recommend seeing GCM paint in person first before making your decision.
My R/T has the GCM paint with the stock hyperblack rims. That color combo on the R/T, in addition to the black side steps and splash guards, is masculine but distinguished (it's not black and it's not silver, but somewhere in between which makes it stand out). It may be a popular color on the forums, but it's not a common color around these parts.
White and black are the common colors on SUVs (on any vehicle, really) where I live.