Bahamas sailings are short by design — 3 to 4 nights out of Florida — which makes them the easiest cruise to say yes to and also the easiest one to regret if you go in expecting a proper holiday. Two days of actual sailing means two port days, one private-island day if the line has one, and not much slack.
MSC Seaside — 3-Night Bahamas, round-trip Miami (3 nights) — Does exactly what a 3-night Bahamas run is supposed to do — Nassau, a private-island day, back to Miami. Nothing more, nothing less. Good value per night if you're not expecting a full itinerary.
Norwegian Sky — 4-Night Bahamas & Great Stirrup Cay, round-trip Miami (4 nights) — The extra night buys you a full sea day, which the 3-night sailings don't have room for. Great Stirrup Cay is Norwegian's own private island, and it's the best part of this itinerary by a distance.
Year-round is fine given the short sailing length, though winter weekends get crowded with the same short-cruise crowd looking for the same thing.
Miami and Port Canaveral, both a short flight or drive from most of Florida.