Williams train does not hold a candle to a steam driven trip along the Animas River, though I'm glad you enjoyed it. I still remember being disappointed in the Santa Express from the Riverside Plaza, Xmas 1959. Durn thing stopped part way up Cajon Pass, way short of the 138, and Santa came out from behind a rock through thr dry grass and weeds. Waved at our train car, never set foot in it, though he did board the train. And I KNEW it was just a siding in a Cajon Pass, even though I was 5.
Things improved upon my return to the Plaza, where my mom was clowning with an old high school chum, Oscar Meyer, just outside the Wiener-mobile. I got a wienie-whistle.
You need to take your family on the Durango-Silverton narrow-guage railway in SW Colorado. Your son will love it, and everybody will remember it their whole life. Incredible views, incredible engineering.
But don't waste your money on that Williams to Grand Canyon spur in AZ. Real disappointing.