I think it would be interesting to work with a black and white tartan. For daywear you could continue the monochrome with a black shirt and silver/gray tie, etc., but if you went for color, I would stick to muted (heather colors) for the shirt, hose and flashes, varying the depth of color for interest. Varying degrees of plums, olives, soft yellows for daywear? With black and white, your palatte is blank, and you could get very creative with the color options. I'd love to see photos if you decide to go with your clan tartan.