Congrats and Welcome to the club CruiseDad!:D
Jim pretty much covered most of the perks I use as well. There are a few more though.
Guaranteed Dining Assignments.
Guaranteed Steakhouse Reservations.
Petit Fours delivered one evening by Room Service.
Does anyone know if we are still getting the Galley Tour?
One neat and un-written perk is the "Welcome Backs" you get from the crew when you hand them your card the first time.:)
There is an On Board Credit when you reach Milestone Platinum which is 25 cruises. On the 25th cruise you get 25% of something as an On Board Credit.