Once again, I find myself compelled to defend ports-of-call that aren't "Disney-fied". If you're squeamish about being approached by natives who have funny accents, stay on the boat. For those who believe that one of the pleasures of travelling is to experience the flavor of other places and cultures -- for better or worse, you'll probably enjoy Freeport and Nassau. My advice in either port is to move a bit away from the disembarkation areas where local "entrepreneurs" descend upon the cruisers. Take a cab to PI and hit the upscale version of the strawmarket there -- less people, less hassle, same prices on local crafts, trinkets, clothes, and artwork. Hit the Hurricane Hole under the bridge and have a tropical drink and a great grouper sandwich while walking the docks where the charter fishing boats come in.
Remember, you're on vacation, so it's supposed to be about you. If running the gauntlet off the boat isn't your thing and you don't care to be exposed to a different standard of living, you have a world class cruise ship to play on. But for those who are the least bit curious, I would suggest that if you get off the ship with a positive attitude and with one hand on your wallet, you'll have a fascinating, fun experience.