I tip when I detrain, like RitchieRich, for general service (including ice). If I request an in room meal (seldom), I tip extra for the meal when the meal is delivered, though. Some people tip beforehand (aka, bribe), I tip for services rendered. I usually tip $10 night for acceptable service (puts the bed up and down at requested times, gets ice on occasion, is in the car at least sometimes), up to $20 for really good service. And I've tipped zero with a call to Customer Relations for bad service (dictates when bed will be put down, doesn't do it at all, never in the car).