In addition to the obvious train ride, the entire company town of Cass has been preserved. There is a huge company store, houses, etc. There are tours offered of the town and railroad shop. There are also the burned remains of the mill. Lots to see here. The yards are accessible to the public, you need to be on a tour to go into the shop buildings.
Recently I have been running the Whitaker train on Tues and Wed. But that changes from week to week. If you can hang around to Thursday, come up to Durbin and ride the "Durbin Rocket" powered by one of only 3 operating Climax locomotives in the world. My regular gig is running the Rocket Thurs-Sunday.