I love trains as long as the trip is under 8 hours.
I've done Amtrak from Minneapolis to Missoula, Montana. It took 36 hours. Such a long 36 hours. After a while, you just start to go... ok.... id rather be doing something cool in those mountains than just looking at them. I much prefer road trips because if you like what you see, you can stop, visit, take photos and then continue on.
I would much rather take Amtrak than Greyhound... Did Greyhound from Frisco to Los Angeles... terrible experience. I've taken it a few times since from Frisco to Denver since it's only $15 and usually there are a few people going to the airport so it's less weird... but for long distance, no thanks.