[QUOTE=darben;17871360Of course the Empire Builder out of Seattle will take you to Glacier National park.[/QUOTE]
I took the train to West Glacier, was picked up by the lodge van, and spent three days at the Lake MacDonald Lodge. There are free shuttle buses over the Going to the Sun Road, as well as the Red Bus jammer tours that aren't free. I didn't see everything I might have if I had a car, but I did see a lot.
Another option is Yosemite. You can book a ticket on Amtrak straight to the park (the last leg is a bus, of course).
What's going to get you is hotels. As others have said, it's often hard to find a chain hotel (especially Hilton) near National Parks.
In any case, the Coast Starlight is a wonderful train, and the one-zone redemption for the family bedroom can be a great deal.