First off, and mor eimportantly I think, if you are wearing the jacket and tie go for the white dress shirt. Mayching the shirt to the hose is more of a casual rule in my opinion. Dressy should almost always be a white dress shirt.

I think the charcoal hose would look good, mind you I wear charcoal hose and a charcoal coat or vest with my Ancient Watson all the time (look in my album listed in my signature). You may also consider Lovat green hose as they may match the tartan and the tie very well. The flashes will still pop, but will be a bit more subtle with the lovat.

Just my opinion.