Okay, I'm back at my computer!
First of all, I have a Pinterest board with a lot of travel wardrobe ideas including a lot of capsule wardrobes: http://www.pinterest.com/msmar.....obe-ideas/
Second, think about layering on the plane - wear your heaviest shoes and carry as many pieces as you can on your body! LOL
Third, if it were me and I didn't have a tight flight timeline, I'd re-think limiting myself to a carry-on. It gets hot and sweaty in the Caribbean, and for me part of the fun of a cruise is having a lot of fun outfits to wear. The cruise cabins are set up to store your suitcase under the bed and for me the extra trouble to check a bag is worth it.. Your mileage may vary, of course.
Fourth, you can always buy hats at the ports. When I went to Vietnam in 2012 I bought straw hats for, like, $1 each and just left them behind for the flight home. If you do want to pack one or more, try stuffing clothing into the crown of the hat to hold the shape and that way it won't take up much space at all.
Finally, if I were really limiting myself, I'd pack bottoms in neutrals: black, white, olive, maybe red. Those colors go with pretty much any color top and you can mix and match tops with any of those bottoms. For tops I'd take tee-like tops but step it up a notch with nice fabrics and shapes, like the Ted Baker tee below. Then add dresses for the fancy dinners and you're good to go. It gets cool in the a/c so I'd add a topper like a linen blazer or maybe a denim jacket. If I wanted to be fashion-forward with my footwear I'd take my silver Birks and white loafers. And for the fancy dinners I might take my awesome black midi and a couple of dressy tops, and some dressy shoes. (And FYI some people ignore the dress code for dinner, although I think it's super fun to participate!) And a nice belt doesn't take up much space and can dress up a simple outfit.
Oh, and pockets are good so you can put your card-key (which you also use to pay for drinks) in 'em!
