Julie, I am seeing mixed media trench coats this Fall. Check out the Sam Edelman Double Breasted Wool Inset Trench Coat and The Burberry Brit 'Crofton' Leather & Twill Trench Coat at Nordstroms for examples. (Sorry having trouble with linking to these).
Of course a classic taupe, tan, or black will always look classic and cool. It's good to get one that compliments your natural coloring.