Oh, well, if we're morphing away from Amtrak dining experiences, I had a memorable meal on British Railways in 1985. My brother and I were tootling around the country on a 2nd class Britrail Pass, and our final ride was back to London from Penzance, a 6-hour ride. (Most of our rides during the trip were too short to be too concerned about on-board service, but we sometimes bought tea from the refreshment carts that were pushed through the 2nd class carriages.)
We found out that this train had a "restaurant car" and since we were near the end of the trip, decided to try it out. It was basically a First-class carriage fitted up for dining, which didn't really require much, as all of the open coaches, first and second class, had facing seats with fairly substantial tables. The table was set for dinner, with china and silver. The food was cooked in an adjacent catering car. Dinner was 25 pounds (which was about $30-$35 at the rate of exchange at the time), and this was 1985, so that was a hefty chunk of change. But it was a full dinner, and not a bad value for a one-off. I had the steak, which was cooked very nicely. The main thing I remember was that, in addition to dessert, they served a cheese course at the end of the meal, a large plate of cheeses, warmed to room temperature as they should be, served under a glass cover. I don't remember whether the price included wine or not, although I suspect it didn't. Off the train, we never spent more that 10 pounds or so for dinner, but then we were eating at a lot of Indian restaurants, and at the time, the Indian food in London was far superior to anything that was available back home. (My brother had just returned from a semester in Nepal and a tour of India, so he introduced me to the unusual stuff on Indian menus that I had never tried before.)