Many years ago my father was a conductor on the passenger train, on a section of the trip through British Columbia. I got to ride in the lead engine through the Rockies when I was maybe 8 or 9 years old. Incredible views and scenery. Lots of wildlife too, although much of it disappears into the trees when the train approaches.
The train overnights at various places where you stay in hotels etc...or at least it used to.
If you can afford it, do it. The section up through British Columbia and into the Rockies is spectacular and you will never forget it.
I don't think it matters all that much what time of year, but I'd suggest any time spring through fall....each season has something going for it. Worth noting that the autumn colours are incredible. Winter is too cold for my liking these days.
