One more thing about tipping:
There are a few additional tips involved. You will want to have cash for this purpose so pack lots of singles. Like Smoose said, you will need to tip the dock workers who take your luggage when you get to the ship. Those workers usually get the same buck-a-bag tip that you would give to anyone who handles your bags, (like a hotel bell hop, etc.) More if you've packed a set of barbells in there.
On the ship, room service is free, but a small tip is standard. One buck if all you've ordered is coffee for the two of you; two dollars if you ordered a full meal.
like Smoose said, frequently we have received such excellent service from our room and wait staff, that we want to tip extra. For this we use cash also, and this additional is given in person.
Then at the end of the cruise, when you are leaving the ship there are porters who will help you take your luggage from the luggage claim area to your taxi, or shuttle. Same as at embarkation, a buck or two per bag will do.
