Oh man. This is SO open to interpretation.
I guess it's what kind of image you're trying to convey. Most straight benchwork I've seen is painted black or dark brown to reduce it's impact on any nearby scenery. Some have gone so far as to cover it entirely with black felt, or some other non-descript cloth.
I've already figured my layout will be "encased" to keep the felines off it, so I'm going toward a red-oak or walnut stained "cabinet" around the layout, with plexiglas or glass panes between the lower portion and the ceiling. This should give it a nice museum feel.
So...what do you like? Black, brown, grey, etc, or stained wood?
How about floor to ceiling scenery such as John Allen would do?
Michael