We booked this tour during our recent cruise stop in Skagway. Selected the 8:30 option to take the bus up and the train down. Much better option since the train tends to be less crowded coming down. The bus also stopped at a few sites for pictures.
Driver even pulled over when we saw a bear on the side of the road.
The train is offered on it's own or through ship excursions however, the guide was great going up to the pass. Well worth it to hear the details about the history of the area.