Perhaps Disney Cruise should do some combination of numbers and days so you could reach the levels for days or for number of cruises. So you could have something like this (numbers for the nights are just guesses, it could be higher or lower):

Silver: 1 cruise
Gold: 5 cruises or 20 nights
Platinum: 10 cruises or 50 nights
Pearl: 25 cruises or 100 nights 

They probably needed some more levels – at least a 50 and 100 level, maybe titanium and diamond. Things like titanium, emerald, saphire ruby, diamond for the 50, 75, 100 etc ranges.

And then continue on:
Titanium: 50 cruises or 200 nights
Diamond: 100 cruises or 400 nights

A few things I’d like to see at the Pearl level:
1. Priority luggage to your room.
2. Discounts without placeholders would be nice.
3. Bring back the Platinum gathering, except at Pearl I guess.
4. Earlier booking for new itineraries I presume will be part of it, ditto excursions.

On a different note, I do miss the intimacy of the Magic and Wonder where you could see crew year after year and they’d remember you. I wasn’t a fan of the Wish layout, btw, let’s hope the next ships improve it closer to the original 4.