My sister took an Amtrak train to DC with some friends -- she enjoyed the experience tremendously, but I think she had to be at Union Terminal by 4am to catch it.
I used to ride Amtrak a lot when I lived out East. Great service, but I think it makes more sense between places like DC / NY / Boston than it does elsewhere. Cincinnati - Chicago would be good, but that's about the only train I ever find myself wishing existed as a convenience.
23 Years and Counting...