I'm with those who think it should be first come first served too. While small children obviously need to be seated with their parents, I don't see why adults can't sit separately for awhile, or older children, until a pair of seats open up. My friend and I travelled a few hours before we got seats together, we didn't see any reason to make a fuss. I think it's a bit mean to make someone with a window seat move, if they were there first, and neither of us were arrogant enough to boot out those people who boarded ahead of us just because we were lucky enough to have a companion! We got seats together down the track, and what felt like the excessive thanks of the car attendant for what seemed to me as acceptance of the situation as it stood, no worries.
With the rooms I don't see why someone who had booked earlier than another party should be moved. If a group wants to be together then Amtrak should tell them when they book that there are no longer adjacent rooms, but if it is that important to the family they will check with other customers. If I were the family booking I would at that point say, oh please don't go to the trouble, unless it was a situation with many more very young children than adults and if that were the case, a bedroom would be better for at least some of the party. The people to be switched could at least have the choice. I spend thousands of dollars and fly for many hours in order to take an LD trip. I book as early as possible. I check that I get a room upstairs. I don't see why I should be treated as less important than a family. Nor more important either but first in first served is the only fair way to put someone above another in such a situation, and I make sacrifices (it's a lot to pay so far in advance) so that my room is sorted early on.
Dunno, maybe I'm used to valuing fairness over anything!! I felt outraged on behalf of the OP at comments that they were being selfish, when they were first. When I was a kid, the sofa rules dictated whoever got it first, had it all evening. The getting was no holds barred, so long as you weren't disqualified by leaving before being excused from the table and if someone was injured in the racing for it then that was unfortunate but first was first and my brother and I respected that
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