Pewter. Like other neutrals, gray gives you limitless possibilities as far as introducing other hues. However, don't forget to include different textures and patterns, as well. This will keep the more saturated grays from appearing too drab. Here, a pewter (gray with a bit of bronze) wall color is tempered by a host of of fun colors and playful patterns.
Paint Pick: Stone Harbor 2111-50 by Benjamin Moore