We haven't done the Wish yet, but we're DVC members and have been on 3 cruises. We use
Dreams Unlimited (a sponsor of these boards) as our
travel agent. We get on board credit from them and if you're in the US/Canada they send a gift basket to you before your cruise. The travel agent controls the booking (any changes to the reservation and payments go through them.). You do your own online check-in, book port adventures, etc yourself. If you like cruising, you can buy a placeholder booking on the ship for a $250 deposit (refunded if you don't cruise in 24 mths) and it gets you 10% off a future cruise (with a few dates blocked out, usually around Thanksgiving/Christmas/Easter.). A travel agent can be invaluable in that future booking if you're booking on the first day of newly released itineraries as the placeholder booking requires someone to call in, which can have long hold times.
On the other ships DVC members get daily gifts if you check in with the DVC sales desk. They scan your key to the world card. Somehow they seem to always know who is a DVC member! You'll have a magnet on your door, will get free lanyards on day 1 (especially great for first timers who don't get lanyards from
DCL.). They were giving out cinch bags on our last cruise as one of the gifts (previous years we got baseball caps.). They usually have a member gathering/celebration (1hr) sometime during the cruise with free drinks (1 alcoholic, a juice, and bottles of water). It's a soft sale. You watch a video, they play a game, and you get a character meet and greet at the end.