My (now) wife and I took the Empire Builder from Seattle to Chicago about 10 years ago. We purchased a private cabin. We were 8 hours late leaving Seattle and couldn't get into our cabin until we got to Spokane because of some sort of merge of trains coming from Portland and Seattle. Got to Spokane, got our cabin, another 6 hour delay. By the time we reached the upper Midwest, they were rationing food, literally cutt…
All Amtrak lines are operated a little differently, AFAIK. As far as the West Coast is concerned, I find both the Pacific Surfliner and the Coastal Starlight to be pleasant and enjoyable (although not very affordable). The Northeast Regional on the East Coast is pretty affordable, runs often, and makes traveling between cities in the Northeast megalopolis without a car pretty trivial, which is nice.
All that's to say that I wouldn't judge Amtrak by its least-used routes.