Charcoal is a neutral colour and comes in various shades. The only charcoal suit that I have is mid grey. With charcoal I'd go for blues, greens and blacks and purple*. I'd save the rusts, reds and browns for an olive suit, if you have one. But of course it's just my opinion, though I've been dressing like this (paying attention to clothes) since 1980. *Purple is probably one of the most versatile colours around and goes with most colours.