The YouTubes are enlightening. I had looked at some of them previously but didn't pay too much attention because I was ticketed for coach... until I got VERY lucky: I was checking schedules and pricing at the 1-week from departure mark when I discovered that there were no longer coach seats being offered. I called and was told the train was sold out except for a few sleeper rooms....AND the roomettes were now $100 lower than than before - the rep on the phone did say it was their lowest fare! I was able to have my SAVER fare applied to the roomette and pay the difference for the upgrade, very happy because I wasn't sure they would do that! Then, when I looked back at the website, refreshed it, I saw my newly relinquished coach seat available, BUT the roomettes were now almost $200 more than I had just paid 5 minutes before! They are still set at that rate today, 3 days out, a price about $100 more than when I originally booked the coach seat. Interesting to note that the Family Bedroom is now priced lower than the roomette, so my guess it will be occupied by the time of departure.
I don't understand the pricing system, but I am very grateful that I was able to snag a better price at 1-week out, perhaps what is called here a "low bucket" price? I don' t know how to tell what "bucket level" the pricing is at, maybe by experience. I wondered if the good price I got was because the roomette was on the lower level; I was not savvy enough to ask the rep on the phone which car, which roomette number at the time I made the upgrade, but I'm certain I will be happier travelling in #13 than in a sold-out coach.
Again, many thanks for your help and quick replies on this forum. m--