You cannot tip any Couples employee...if they are caught accepting tips, they can lose their job. They can accept small gifts from guests, as long as you leave a note with the gift stating that it is a gift to the employee (so there is no chance for assumption that the employee stole the item). There are people, however that you do need to tip. These include baggage handlers at the airport, drivers, Catamaran Cruise crew, and Spa employees.
Leaving gifts is a form of tipping IMO. When you receive great service[which you will],be sure and get their names and mention them at the end of your stay on the comment card.They will appreciate that more.