I've looked into taking the train a couple of times and balked each time at the idea of paying the same price for 10-15x the transit time. 40 hours in transit is going to be a non-starter for so many kinds of trips, unless you're specifically doing something like [1] where the transit is the whole point of the trip.
[1]: http://www.viarail.ca/en/explore-our-destinations/trains/roc...