Worth is definitely an individual decision. All the perks listed above are nice but by no means required to have a great day on
Castaway Cay. I think part of the "worth" equation is what are your plans while on Castaway Cay? If you are planning on going a lot of other places -- snorkeling, boat excursion, exploring the "other" beach (Serenity Bay if you have a Family Beach cabana or vice versa), going for bike ride, getting a massage, etc. We don't always get a cabana, but when we do, those are the days we just want to relax and having the cabana really helps in extending the time we are on Castaway Cay doing "nothing" (we get off the ship earlier than we normally would and stay later when we have a cabana). Splitting the cost of a cabana between 6 adults certainly makes it seem like a more reasonable price (we think of it as an excursion price per person). I will say on my most recent cruises, even as a platinum
castaway club member logging in right at midnight, cabanas are slim pickings. So unless you are concierge, they can be hard to come by