Flight attendant work is much easier now than before 9/11, when they served meals to all the coach pax on domestic trips. Now, of the US majors, only CO still serves hot meals in coach. FAs elsewhere spend long periods reading US Weekly or other such mind-broadening fare, or griping about their lower salaries and bad working conditions.

Amtrak sleeping car and dining car work is unquestionably harder if they do their job - certainly more physical. Dining car work more tricky than in a restaurant due to train movement, but they earn far more than restaurant waiters. Not sure how hard Amtrak coach attendants work. And always, there is considerable variability in individual performance and visibility.

If they do a good job, I would tip my sleeping car attendant $25 for a two-night trip, at the end of the trip. In the dining car, 15% added to each pre-tax bill or equivalent (sleeper pax get free meals).