And when I think about using a whole rainbow of colour, I know that I'm going to place them on a neutral background; Black, white or kraft. It may be the heaviest visually of the three but my preference has to be black. The colours come alive more and well it just has that more perfectly graphic feel to it.
Doesn't all that colour just make you happy? It's certainly joyful to see it spread all over my crafting table when I'm playing around putting cards together.