Welcome back, Deborah!
I do like to try the Drink of the Day specials when we're sailing, and they are offered in a regular cup or the souvenir plastic cup which costs a bit more. I usually get the souvenir cup with the first drink so I can keep it to take home. You're welcome to use it later in your sailing for refills on drinks and you'll pay the same to refill that as you would the regular cup, though I think you get a bit more in the souvenir cup since it's just a bit bigger.
Once we're back home, it's fun to pull out our Disney Cruise Line souvenir cups and mix up a batch of our favorite Castaway Cay drink, the Konk Kooler. You can find the recipe online, but it doesn't taste quite as good on my back porch as it does relaxing in the sand on Castaway Cay. But, since I live in Ohio and not on Castaway Cay, it's a close second!
If you have beer drinkers in your family, check out the refillable beer mug in the
Beer Mug Package on the Gifts and Amenities page of Disney Cruise Line's website. If you pre-purchase it, the mug will be waiting in your stateroom and you can just take it to any of the bars onboard and get it filled up for a discounted price. You'll get 22 oz. for the price of 16 oz. They also offer a token so that when you're done, you can trade in the mug for a token until you're ready for another drink, then you'll get a new mug with the beer refill. My husband prefers this so he doesn't have to lug around the big mug, though we do bring it home at the end of the sailing.
Have fun counting down these last 38 days until you set sail, Deborah!