Here ya go, Oscii:
From a landscape point of view, the first part of the route is pretty dull - miles and miles and miles and miles of flat monoculture farmland - but experiencing just how flat and monotonous it is, taking a full 24 hours to cross with someone else doing the driving, helps to put a lot of "middle America" in context.
This is also a good time to get chatting to people! Either in the dining car, seated 4-to-a-table (always, no empty spaces) or in the observation car:
The old guy in the picture above was one half of a set of grandparents who were taking their grandson on a train trip specifically so that he'd know what it was like to take the train, as he might never set foot on one again!
... and as you can see, the observation car offers a way to view the landscape not provided by any of our European trains.
(These are first-come-first-served seats, all taken during the day, but mostly empty at night when the passengers with accommodation go to bed).
If time allows (and it usually does) it's worth getting off the train at the intermediate stops to visit the station, as most of them are "attractions" in themselves. Functionally, they're completely disproportionate to their use, as they'll only serve two trains a day (one in each direction) - but you can get a feel for how important the railways used to be back in the good ol' days. This is the station in Denver:
Once you get past Denver, the view changes quickly and quite dramatically as the train heads up and over the Rocky Mountains. There's one section where the only transport routes are by rail or by foot, so if you're inside looking out, you won't see any signs of human presence at all. This is the slowest section of the route, where the train crawls up the mountains, and IIRC there's one point on the Pacific side where it's bent back on itself at about 200° - but it's not this one!
If you know your trains, you'll see that this is a "triple header" - three locomotives at the front, all needed to get up the hills, but not always all up to the job. Breakdowns are very frequent, and if one goes, the others can't manage ... hence the "fluid" timetables.
Because they put all the locos at the front, it's possible to make your way to the back door and look directly behind the train in a way that you can't do with our European double-ended trains. This allows one to further understand why delays often happen - there's only one set of rails! If a goods train is trundling in the opposite direction, the passenger service has to pull in to a siding and wait for it to pass
(and wait, and wait, and wait - the goods trains can be 200 cars long).
Because it gets the flatlands out of the way first, I think Chicago -> SF is a better direction to travel (rather than SF -> Chicago), though I also have a thing about "coming over the mountains and down to the sea" ! This does mean, however, that you arrive in/pass by Salt Lake City and that part of Utah in the night and don't get to see anything. Unless the train is several hours late, which it might be.
Great program, I'd love to follow the journey he took someday.
Not this week. I made the decision over the weekend to rip out the last of my tomatoes after the blight made a rapid comeback. 
but when yerman asked me the purpose of my visit and I said "doing an Amtrak tour" he wanted to know all about it, and how much it was going to cost, and then started complaining that ordinary Americans couldn't get such good rates ... at which point I suppressed my natural desire to tell him that the passes are freely available to anyone who wants one! 
.
. Anyway, great news - Aer Lingus produced the goods...finally. But....small print says it only covers the aer lingus leg 
. So, I'm looking at flight to Chicago, and hop on the California Zephyr. Have you been on this? Any tips? Tripadvisor is good enough, but I wouldn't mind an Irish angle 