No, but sign up for the Romance Rewards and then use the online early check in, 3 days before you leave, that way you can speed up the check in process and get your room liquor order in. If you don't that is no big deal either. When you get there, you will be well taken care of once you reach the Couples Lounge and give them your name and which resort. It is good Mon!
Nothing in the mail, but you might want to do the pre-registration thing online through the web site. Not required but it helps to speed things up a bit when you arrive. They will know you are coming both at the airport lounge and at the resort when you get there. No problems, really. All you need to worry about is packing and getting to the airport on time.