Actually, I think this is one of the things RCI has gotten right. On CCL, they add the tips to your account and you basically walk off the ship... With RCI, you can still have the auto tipping thing (so you don't need to have a bunch of cash for the last day) but they give you the voucher and envelope so you can actually hand a tip to those you feel deserve it and thank them.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007