We spent 12 days on Royal Caribbean's Navigator of the Seas.
I think we had maybe 2 days of sunshine on the crossing. Fortunately, the ship has a lot of interior space. This is "The Promanade", a five storey atrium space lined by shops and restaurants.
And the gym gave us a place to stretch our legs when it was too windy and cold out on the running track (5 laps to the mile).