The color gray is an unemotional color. It is detached, neutral, impartial and indecisive - the fence-sitter. From a color psychology perspective, gray is the color of compromise - being neither black nor white, it is the transition between two non-colors. The closer gray gets to black, the more dramatic and mysterious it becomes. The closer it gets to silver or white, the more illuminating and lively it becomes. Being both motionless and emotionless, gray is solid and stable, creating a sense of calm and composure, relief from a chaotic world. The color gray is subdued, quiet and reserved. It does not stimulate, energize, rejuvenate or excite. - Color Psychology
The color gray provides that certain calmness to your interiors. And when you inject a happy color here & there, you break the monotony. Just like beige, gray is classy & classic.