On one of the other message boards, there was a discussion about this topic. Apparently the "freestyle sun decks" are meant to be "top optional". We sailed the Jewel but never made it up to deck 15 to see for ourselves (I didn't let DH know about this option ), and I doubt that anyone will be using it for that purpose when we sail on the Pearl to Alaska in May.
As far as I know, the Jewel and the Pearl are the only two ships yet with this "freestyle sun deck". If that is something that you're really looking forward to, I'd do a little more research to see what you can find. The areas marked as the freestyle sun decks are on deck 15 of the deck plans for both ships.