Yes, the other reviewers are right. It's a great piece of history with excellent exhibits and cool trains. Yes, bring a lunch and make an afternoon of it. Yes, call for the times of the train exhibition because the demonstration is half the trip.
Now for the part they didn't mention. We ventured past groups of very friendly horses about fifteen miles down the road to the Spiral Jetty on the Salt Lake. In August the water was low and it was possible to walk all the way out to the jetty. For me, the lake itself is an eerie place. No signs of life in the water or on the water. But walking this artistic "earthwork," added a nature and art element to the historic element of the Golden Spike site.
See more about the Spiral Jetty here>>>> http://www.robertsmithson.com/earthworks/spiral_jetty.htm