My first cruise (1991-non-disney), went out of San Juan, and had no sea days (7 days) and you got off at a different Island every day. It was fun, but you always seemed to be rushing, off to do tours, on before the ship left. When I was on the Magic in March, I wondered, what do you do on the boat at sea.
Lots, I would not give up a sea day for anything. Even just to relax and exjoy the sunshine, those Sea days are the best. I like the idea of San Juan (very nice place to visit would like to go back) and Antigua, very nice place to visit and if I'm remembering correctly they have 365 beachs.