Excellent question! Firstly, you may want to tip your sleeper attendant $5 per night per passenger, more or less depending on service.

In the diner, it's customary to leave a tip of 15-20% of the printed meal prices, even if you're in the sleeper. In fact, the crew is most grateful when sleeper pax remember to tip, especially since they're more likely to be affluent and thus generous tippers.

Your tip in the diner will go to the waitstaff, as the steward who seats you and handles cash receipts cannot accept gratuities (Nor can the chef, food specialist, or the train's operating crew, including the conductor and engineer. Of all of the above, you will likely encounter only the conductor!).

You may also leave spare change for the Lead Service Attendant (lounge/bar attendant).

In case you were wondering, all meals include milk, tea, or coffee, plus one can of soda or one bottle of water for sleeper pax. Booze and extra orders (i.e. pie a-la-mode, which is now considered two desserts) will cost you.

Have a safe and fun journey! ^