I think this is very easy. The two that get the most, the head waiter and room steward can be changed to either up or down. However, I can't imagine down. They would have not to show up at all for all the work they do. We tipped extra to both the last night and were happy to do it and they were pleased to get it also. As we were leaving the ship to wait for our color to be called I looked at these people faces and they were hard at work for the next group. Can't imagine being chipper all the time and wanting to know or even care about who is on board. They work so hard and really the only money they make is tips. My room was cleaned all the time, we had food presented to us in the dinning room and it was delicious so was happy to tip extra.
On Princess, you can always go to the Purser's desk and have the automatic tips removed ... then, you can get vouchers in the amount you wish to give and to whom and these will be charged to your Sail and Sign card.
I cruise the Emerald Princess, Eastern Caribbean on April 16, 2012