The train trip takes a couple of hours each way and goes through scenery that is otherwise inaccessible except on foot. You get to explore Silverton, an old mining town, before you head back. It's totally worth it, and it's an old steam locomotive and you can ride in an open car if you want. Great experience.
^^^ This! About 3.5 hours up and the same back. There are also options. You can take the train both ways, or you can take the train up to Silverton, and take a bus back. Did the trip again for the 3rd or 4th time this past October, and did up/back on the train. Different perspectives each way. And you're not stuck in one place. Yes, you get reservations for a specific seating in one of the cars, but there are gondola cars that are open air and anyone can go there and sit or stand anywhere. Definitely the better option for photo ops. And ~2 hours in Silverton, have a bite to eat and mosey around town exploring. Great way to spend a day, the kids will be pretty tired when it's all said and done!