If you want something very similar to the three you named, do not sleep on Case of the Golden Idol.
It might have a little more replayability due to they way decisions you make impact the story, but I'd also put in a strong recommendation for Pentiment.
Roughly 18 years ago, my buddies and I took the California Zephyr from the Midwest out to San Fran. We were riding coach and it was two days travel each way.
The train was fine--about what we'd expected, nothing amazing but in generally good condition. The trip was great, though. The scenery traveling across the west was almost always interesting, we played a bunch of poker, and we met a bunch of interesting characters we still talk about to this day.
The most interesting guy we met (we dubbed him "The Stranger" after Sam Elliott's character in The Big Lebowski) was a guy who made an annual trip coast-to-coast and back. He had some kind of grift where he was getting unemployment checks from two different states and would schedule his Amtrak trips such that he'd always miss his Chicago transfer and get put up in a hotel so he could shower and sleep on Amtrak's dime. He'd mail a suitcase to his destination with clean clothes, cigarettes, etc, and mail his dirty laundry back home. When we got struck with a delay in California, he left the train station and bought a bunch of pizzas at a nearby Domino's for the passengers and staff.
I highly recommend it as an alternative to air travel if you can spare the time. I often think about doing it again.