I rode the geology train in 2014 and it was FANTASTIC!
Part of the fun was riding with a bunch of people that would not ride the train otherwise.
A highpoint was getting off the train, walking through rock tunnel and getting an up close look at the Garfield Monument while waiting for the train to come thru the tunnel.
The geologist types were encouraged to collect rocks in the tunnel!
Learning about the history of the area millions of years ago.
The docent / geologists were all great and super informative, but at the same time did not blather on the whole trip. As I recall we stopped at a location, they talked, then we continued to the next location and they were available for questions.
Especially if you have ridden the C&TS a few times, this is a great opportunity to look at things in a fresh new way.