I got into an... Enthusiastic interaction lets say with one of the Spa managers on the Disney Dream. Wanted to purchase a Day pass, but the front desk said no, so I asked to speak to the manager and was basically told "Each ship does it how that manager decides" so some will offer day passes, some only the Length of Cruise Pass. I know I saw someone on here mention one of the other ships was advertising day passes on a sign by the spa desk.
Honestly, it used to be one of my favorite things but when they doubled the price (17 dollars to 35 or 39 or whatever), It was easy to let the Rainforest Room go. Its just not worth what they want to charge.