At human levels of expense, I think it's not. I traveled Amtrak sleeper on a 24-hour ride. There was no shower, so I couldn't have gone 48 hours, but otherwise

At human levels of expense, I think it's not. I traveled Amtrak sleeper on a 24-hour ride. There was no shower, so I couldn't have gone 48 hours, but otherwise it was end-to-end way more pleasant than any international flight I've ever taken.