I would refer to the factory's color charts, where you can actually see the colors, to see if they have the qualities you like. 'Flake manufaturers will tell you on the chart what base they are shot over.

If that doesn't give you what you wnat, spend a couple hours in the shop, shoot several base colors on some scrap, and then 'flake over the top to see the difference. Pick the one you like best.