This may be a little late, but perhaps it will help someone else who has the same question....
As several other people have already mentioned, the decision of whether to go on an all-inclusive resort-type vacation or on a cruise comes down to personal preferences. The main question to ask yourself is "What do I like and how much of a priority is it?" Granted, I think that is a hard question to answer unless you have done both. My husband and I have done both within the past 2 years (2 all-inclusive trips and a cruise on Carnival Inspiration where we visited Grand Cayman, Costa Maya, Cozumel, and Belize).
In our collective opinion, and this is JUST OUR OPINION - which really means nothing in the grand scheme of things, we like the all-inclusive option best. It's not that we dislike cruising, for we enjoyed our cruise very much, it is that the all-inclusive option is our preference if given the choice.
At the 2 resorts we have stayed at (Cancun and Puerto Vallarta), everything was paid for up front - all meals, sodas, alcoholic drinks, and basic watersports. At our resort in Cancun (Moon Palace), our plan also included unlimited excusions/tours and unlimited access to their golf course. **Not all resorts offer excursions in their all-inclusive plan, our resort in PV did not. You will have to check on the specifics of the resort you are looking at.** On the cruise, we had to purchase a "soft drink card" so that we could get our morning caffeine fix (we are not coffee drinkers) and we had to pay for each and every alcoholic drink we had. Granted, we are not big drinkers, but 1-2 drinks per day over 7 days does add up... We met one couple who brought some sodas, vodka, and rum along in their luggage, but that just seemed like too much of a hassle for my husband and I. (But hey! To each his own, right?) The mainstream cruise lines, boast that cruises are "cashless vacations," and in one sense they are. In order to purchase drinks and other services on a cruise, you don't have to carry any cash, however that doesn't mean it's included in what you have already paid. Carnival has a "Sail and Sign" card that you present whenever you buy something and before you get off the ship upon returning to port, you must settle up on what you have "charged" during the week. I am not sure how other cruise ships are about paying for drinks and suck. My husband and I were very conscientious about what we "signed for" on the cruise and this allowed us to stay within a budget. We didn't book our shore excursions through Carnival either, we booked through private tour operators online before our cruise and that helped cut down the cost as well. One couple who dined with us every evening, however, were not as conscientious and they were quite shocked when their bill arrived. They couldn't believe how quickly the sodas, cocktails, and shore excusions added up.
Spa services at most resorts are not included. That is one thing that all-inclusive resorts and cruises have in common.
Another feature we like about the all-inclusive resort vacation is the ability to stay at one location longer than one day. My husband and enjoy exploring a location in-depth and submerging ourselves in the culture. During our cruise last summer, we felt that we were not given enough time to do this at 2 of our ports of call (Grand Cayman and Belize). We realize, however, that this is an appealing feature to many folks - the opportunity to visit several different locations during a short period of time and only having to unpack once.
A definite PRO for a cruise is that it would allow you to "sample" a destination before committing to spending a week there. Even though we felt like we didn't have enough time to explore Grand Cayman and Belize, it did give us the opportunity to sample them and determine if we would like to go back one day and spend several days there. (Yes, we would like to go back to Grand Cayman and spend several days. We would not want to spend more than a day in Belize City. However, we would be interested in staying at a resort on one of the cayes.)
So, what it all comes down to is personal preference. If you like being able to visit several places during a week's time - then cruising is probably the way to go. If you would rather spend some time really getting to know a particular place and culture, then I wouldn't recommend a cruise. (There are some exceptions, however, like a cruises that stay in one general area like Hawaii, etc). If you are operating within a budget and want to know that there will be few (if any, depending on the resort) additional expenses, then I would recommend an all-inclusive resort. If you don't mind "charging" things and having to pay for things like drinks, then a cruise would probably work for you.
Each option will provide you with unique experiences no matter what. Even though my husband and I prefer the all-inclusive resort option, I'm sure that we will go on another cruise one day (Hawaii, South Pacific, Mediterranean perhaps).
Either way... have a great journey!