Being short is probably the biggest decider - I went around the indochinese peninsula on sleepers a few years ago, and my wife, pretty much on par with the average height for the region, slept like a tot, found her bunk spacious, while I, several SDs above the average, awkwardly wedged myself into my coffin and encountered every jolt through my bones - and believe me there were a lot of jolts. They stop everywhere, and there’s plenty of shunting.

But then again some sleepers (Shiki-Shima in Japan) are like being in a luxury hotel. Rather enjoyed having a soak in the tub in my suite.