I think going with separates you can mix and match would be good. I don't know how long the cruise is or if there will be any need for formal attire. 3 or 4 tops and 3 or 4 bottoms that are interchangeable will give you at least 9 outfits. If there is a formal, then black pants or long skirt with a sparkly top is probably fine. And the pants or skirt could be part of the other options, too. I've never been on a cruise, but I love separates as it gives me more options.
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