It generally takes 2 full days at sea to get to the caribbean which will then provide a warmer climate.
in answer to your question about cabin size we have cruised in various sizes but now stick to the cheaper insides as we do not spend very much time in our cabin (theres too much to do on board!), as far as i am aware there is not much difference in the size on royal caribbean to an oceanview and inside.
Rome (Civitavecchia) : Kotor : Corfu : Rome (Civitavecchia)
Now from £489pp
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UK : Hong Kong : Sanya : Singapore : Phuket : Cochin : Mumbai : Dubai : UK
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UK : Sydney : Papua New Guinea : Yap : Koahsiung : Hong Kong : UK
Now from £1999pp