Bill-
The parlor/presidential class cars Alamosa, Cinco Animas, and the Nomad all run at the back end of the train they are on. They run on different trains in daily service. The trains are turned in Silverton in entirity, so the first class car is always at the back end of it's train. All 3 cars have rear platforms. Cinco has the roomiest platform.
The Silver Vista is spotted immediately ahead of the Alamosa.
Since you are coming out in mid October, you may want to know that
Silver Vista ($129) will run until October 13th
Alamosa ($119) will run until October 27th
Cinco Animas ($149) will run until October 13th
Nomad ($149) will not run after August 15th on regular trains.
(information as of the time I looked at the web site today)
Whatever car you ride, try to get a seat on the right hand side for the trip to Silverton.