I had never really thought of route planning as a hobby, but now that you mention it, I do spend a lot of time doing that for myself and others, but more for air travel. I used to spend a lot of time scouting out bargains on bestfares.com.
Passenger trains run thrice-weekly here in the 4th largest city in the USA, so there's not a lot of choice in the schedule. You can go west to Los Angeles or east to New Orleans. I've never actually ridden that train, but I have seen it go by, so I know it's not just a myth.
I have taken Amtrak trains along the Pacific coast and in New York state. I've also taken trains in Canada, Europe and Japan.