I've done one 3-night (DCL,) one 4-night (DCL.) and one 7-night (RCCL.)
I think the 3 and 4 night cruises are good for those of us who are fortunate enough to be within easy driving distance of the port, although the 3-night really did seem too short, for us. The 4-night was a nice getaway.
I didn't even get off the ship at Nassau. My second trip to Castaway Cay, I just did the power walk that was offered, had lunch at the buffet, and headed back to the ship. I'm pretty meh about Castaway Cay. I didn't find it to be quite as wonderful as most people, but then, I live on the beach, so I'm pretty spoiled, that way.
I think I may try the patch, on my next cruise. I used Bonine on the Mexican Riviera cruise, and I found that it made me very lethargic. I only need it when the ship is rocking, but I hate that groggy feeling. It pretty much wrecked my day in Mazatlan.