As Charlie has noted after WW1 the cars changed from a deep Tuscan red to "Pullman Green" or olive take your choice as to name. I have heard it suggested that this was an attempt by RRs to suggest that their accomodations were equal in quality to "Pullman Service". I have also heard it suggested that the move was the result of the great prices available on "Army green" paint at the end of the war. "Ya pays yer money and ya takes yer choice". At any rate the color changed.
Now while new Pullman green has a nice rich look it soon fades to a color (both in Alaska and the southwest) that resembles army olive drab.
Your most powerful form of advertizing is the pictures of your train either in calendars, on brochures, on postcards, or perhaps most importantly the pictures that Mr. and Mrs. America show the neighbors of their vacation in the Rocky Mountains.
The Silverton is identified with "Rio Grande Gold" it is a photogenic color and you cant pick up a Colo scenic calendar without seeing a D&S pic.
If you paint the C&TS cars Grande Gold all you do is advertize the D&S (a fine RR but not your goal).
My humble suggestion is paint the cars or at least one train Tuscan. Its historic for "Hey Day" passenger service on Cumbres Pass, its a beautiful color which photographs well, and it is not anyone elses signature color.
I would further recommend that the cars be lettered Cumbres & Toltec Scenic RR since that is the name of the product your trying to sell to the public. Lets not confuse the customers when they are trying to find you to buy a ticket.
Enough of my time on the soap box Ill get down now.
I am glad to see my beloved C&TS infused with new energy. Best of luck to you all.