I would get the boy's input??? If there are some train lovers, the White Pass RR offers some exceptional training. It is loaded with history and scenery. Engineering is also interesting. But I would not look at one tour for 8 people, consider spliting up?? Tours in Alaska are so excellent and costly not to miss and too costly for only a so so interest. You aren't going to have all 8 on the same page.
The Glacier Point tour is raved about so probably a better choice if you refuse to split.