Just an FYI--
Although most everyone in the breed show ring uses black harness, there is nothing more elegant than a really NICE russet harness, under proper circumstances!
QUALITY russet harness requires better leather than black, as it is not 'dyed' in the same manner as black-imperfections in the leather can not be hidden w/ russet, as they might w/ black dye. Russet (not "brown") harness is proper with a NATURAL wood finish vehicle WITH BROWN/RUSSET accents---meaning shaft wraps, trace loops, and often, seat covering. With a natural wood finish vehicle w/ black accents (as above), or a painted vehicle, you would use black harness. Metal trim, of course, should 'match' the metal on your harness.
You don't see russet harness much because most vehicles are painted, or 'routinely' have black accents. There is no particular connection between CDEs and russet harness--you might as often see a russet harness w/ a properly turned out vehicle in a pleasure show as a CDE.
For a good pictoral resource of turnouts, try viewing some Mischka driving calendars. They have some of the BEST driving photos, of all kinds of driving turnouts!
If you want color, remember that conservatively, there are only about three 'colors' that are considered really proper--Hunter green, dark(near-navy) blue, and deep maroon--in light horse driving. Hunter looks quite nice w/ red-based horses, as does navy blue--maroon,not so much. Black is the 'universally-proper' color, but of course, there are beaucoups of them! Of course you can vary the pinstriping, but the most versatile is probably going to be either silver or gold--or, I suppose, both.
Generally, understated elegance is apt to be most widely appreciated by judges, IMO-from someone who has done some judging.
Margo