Cruises are an interesting phenomenon in one respect: The people who criticize them most vigorously HAVE NEVER BEEN ON ONE!!!
I am an experienced traveler and an experienced "cruiser", and a well chosen cruise (ocean OR river) can be the vacation of a lifetime.
There is NO COMPARISON with a driving vacation, on which you are packing and unpacking constantly, driving, eating as greasy spoon restaurants, and are spending lots of money constantly. On a cruise you unpack ONCE, then do nothing but enjoy the destinations and the hundreds of things to do on the ship.
If you are a misanthrope and don't want to be surrounded by people all the time, you can eat at "different" times in the smaller venues on the ship, or call ROOM SERVICE, and eat in your cabin. Either way, the food and service are both generally excellent. Unlike in a typical American restaurant, the servers on a cruise ship WANT YOU TO BE HAPPY, and it shows all the time.
I personally have no interest in the classic Caribbean Cruise (although that was the first that we did, just to get the experience), but consider the very popular Baltic Sea cruises that start in either Copenhagen or Amsterdam, and hit Helsinki, Oslo, Denmark, Estonia, and a few other places, topping off at St Petersburg, which is one of the most wonderful destinations on the planet. You literally can't go wrong.
As for river cruises, they are fantastic. You dock right in the heart of the historic, beautiful town, take a guided tour in the morning, come back to the boat for lunch, then have the whole afternoon and evening to explore on your own. It is so much better than driving.
I have this conversation with friends regularly: they say they don't want to go on a cruise...until the first time, then they plan their whole (retirement) lives around their next cruises. There are also great deals to be had at websites like "Vacations to Go". You can find cruises for almost any budget and interest, particularly if you are flexible in your timing.
I've only met two or three people in my life who didn't enjoy cruising, and that was because they had problems with sea-sickness (not an issue on river cruises). There are drugs to help with that, but the drugs make you super-sleepy all the time, so maybe if you are a person who simply can't stand the gentle movement of a giant ship, don't go on a cruise. But for everyone else, it is an option that you are almost guaranteed to enjoy.