I just returned from a trip aboard the Empire Builder yesterday. Taking photos out of the rear of the Portland Sleeper was a unique experience. There is something to be said about having a sleeper that is at the end of the train, away from the engines.
I was also on the Portland section of the Builder recently, and loved being on the tail end sleeper. Great for photography (travelogue and pics soon). Same trip included the Coast Starlight from L.A. to Klamath Falls, OR (bus transfer to Pasco, WA to meet the Builder), with the sleepers up front. I don't mind either way, though on the Starlight had to walk the train to get good shots of stuff like horseshoe curve north of San Luis Obispo, CA, from the last coach car.
Finally, and to be picky, diesel locomotives don't have whistles. Horns.
Patrick