The one thing that is keeping me from riding the routes that I believe would be the must fun/scenic is the OBSCENE cost of those tickets. Granted, these aren't commuter tickets.
I would love a trip across the high plains and through the mountains by train. Just like I would love to take a cruise from the bottom of the Mississippi to the top.
But them tickets is too high.
In Japan it's quite reasonable to ride local trains. I've been meaning to do a trip along the recently re-opened Tadami Line [1], for example. The one way cost for the full 4-hour, 135km trip is only ¥2,750 ($17).
Though when you add in the costs of getting to the start/end of the line, overnight accomodations, and potentially the cost of getting to Japan first - it gets quite a bit more expensive. But staying at a little guesthouse along the way is also part of the charm.
[1] https://fukushima.travel/blogs/tadami-line-5-sights-you-shou...