not sure how pleased i would be going over a scary death bridge like you can find on youtube, but i enjoy train trips as well if you don't mind the pace.
thailand has 1st to 3rd class, 3rd class you're in for a not fun time if you wanna go potty and man i'd really have to do an overnight, 1st has beds and you can go to another cart to eat or eat in your bed. it's relatively inexpensive. good way to go and wake up somewhere new.
eurail has sleeper cars with 4 beds iirc. like 2 people can't go in at the same time you gotta go in one at a time and throw your stuff somewhere. get in bed, then next person comes in. i don't recall food situations on these i never ate. price not bad at all on these as i recall.
eurail also has assigned sleeper rooms for 2 people and the other side of the room has a bathroom and shower in it. i think these are pricey. my buddy and i paid for regular sleeper room and thought one of these was it when we got on the train. eventually german conductor got to us, checked our tix, didn't speak any english but proceeded to get real annoyed a couple idiots were in the room, which we saw later on a sign on the door was reserved for people's names which were not ours. we didn't use the bathroom (it had a sealed paper thing on it) for which he seemed relieved. he then kicked us off the train in the middle of nowhere at midnight. we ran down to other cars and eventually found one with a couple seats to make it on to.
i've never done amtrak, i have too many freq flyer miles now. i was looking at going to new orleans and back in i think some kind of business fare but never did it and let the amtrak miles i was going to use for it expire. i picked up an amtrak cc for the points at one point. not sure you can do it now but it seemed like you could accrue enough amtrak miles for life at the time.