OZ,

Actually the sleeping car attendants make a decent wage, but that still doesn't mean that they don't appreciate tips. The general average is $5 per person per night, provided that they have done the things that they should do. Of course more is appropriate if they do extra things, like perhaps fetching you hot water for tea from the dining car.

The attendant should greet you at the door, come by after departure to explain things in the room and see if you have any questions. They should also ask if you wish a wake up call in the morning at some point; setup your beds for you at night in a reasonably timely manner (keep in mind that they have lots of beds to do); return the room to its daytime condition in the morning (the best notice when you've gone to breakfast and do it while you're gone); keep coffee, water, & juice available during the bulk of the day for you; and freshen the public bathrooms & shower.

They are also responsible for opening the door at each stop where passengers may be boarding or detraining; bringing meals to those who request it (extra tip required for this); and your safety.