In the US, even if you are willing to deal with the vagaries of erratic schedules, long-distance trains are problematic for the kind of hacker tourism that many on HN might be interested in, but still doable. Some observations to share from my own experiences:

Multi-day long-distances are best experienced in a cabin with a shower facility. These cabins get booked out a month or longer in advance. This cuts down on the ability to make short-notice trip decisions.

These cabins are not lockable except by the conductor. You need to be sensible with your gear, and don't draw attention to it. I took my laptop with me when I went to meals in the dining car or to sit in the observation car.

Temperature control is largely set by the conductor or porter. There are thermostats in the cabins, but I never actually have seen them work.

Internet connectivity on most lines is bring-your-own-Internet; Northeast lines have more options, Midwest/Western/Southern lines are the ones that are BYOI. With a Sprint 3G/4G modem, I mostly got 3G except near the major metro areas, and was able to get some work done, but definitely not anything that counted upon heavy connectivity. Web browsing and terminal-based work via SSH and screen (or similar) was easily doable; anything needing RDP or X11 was pretty much out of the question once you left the major metro areas. VPN is a crap shoot; sometimes the connection is not stable enough. There are vast deserts of absolutely zero connectivity out in the Western US.

Voice phone connectivity is surprisingly good, except in those aforementioned deserts.

Passengers keep to themselves if they see you wearing headphones. It is super easy to find a spot on the train, pop on the headphones (you don't actually need to be listening to anything, or even be plugged into anything), then hit your zone and crank some work out.

Trains are almost ideal for traveling young families. If you are on a $100K-type per annum income and live within your means, then the family cabins that include meals are not a stretch on that kind of budget, many young children are utterly enthralled with trains, and you get to introduce the youngsters to people from many walks of life. Though keep the trip to around two days, and break up longer trips with multiple day stays in towns in between if you can; longer than two days and they start to get bored. Use a car service at either end of the train trip, and it becomes a pretty comfortable way to travel with children compared to planes.

Luggage check-in and pick up is far easier than at airports, but there are limits, and Amtrak is far stricter with sticking to those limits than the airlines with their baggage rules. Trip check-in without the security lines is much less time-consuming than at airports.

Any carry-ons you cannot fit into your cabin are stowed out in the open in some storage bays. This has never presented a problem for me, though at times I have used a locking luggage cable when my paranoia got the better of me. Cabins don't have much storage space beyond what can fit underneath the beds.

If you are comfortable with taking a shower inside the tiny closet that the toilet is in, then you'll be fresh and clean on multiple-day trips. This is the same kind of setup that you have on smaller cruising sailboats. If that kind of setup raises your ick factor, reconsider long train trips.

Meals in the dining cars are generally smaller portions than what you get a restaurant. For Europeans, the portions are normal. Frequent diners of an Applebee's or Outback Steakhouse are going to think the portions are on the small side. The snack bar topped off gluttons like me (I generally try to eat low-carb+high-protein, and carry on board my protein bars and a jar of nuts). On a $100K-type income, the meal and snack prices are not a big deal, though the fiscal and nutritional values are generally absent with some offerings. If you book a cabin, meals can be delivered for dining in your cabin, valuable if you are in crunch mode on something.

Motion was not really an issue; I was very pleasantly surprised at the comfort quality of the ride.

If you stay in a cabin, then tip your porter well when they help you board, and they will bend over backwards to make your trip enjoyable. I tip $50 (which is considered huge and extravagant) and our porters always sought to make sure our cabin was secure and comfortable, we had whatever drinks we wanted delivered to our cabin (water bottles, juices and coffees are served at a refreshments station in the middle of the car), our carry-ons got stowed regardless of whether there was room for them or not, and that we got our pick of meal times (dining car service is by time slot reservation).

I really wish Amtrak would expand their Auto Train service everywhere. Think "land ferry".

http://www.amtrak.com/auto-train

If I had serious FU money, then I would get a private railroad car (or two) built, hitch a ride to someplace interesting along Amtrak's routes, divert to a rail siding, and bounce around the US. I looked into it, and it seems Amtrak actually hauls private railroad cars. There is even an association of private railroad car owners (AAPRCO). I could bring along my own automobile, those diesel-electric engines supply a huge amount of high-voltage power, with that kind of platform and money satellite Internet becomes feasible, and there seem to be a lot of interesting stories out there in those towns (if nothing else I could scout for interesting places for offices).