Cruises can be rather expensive for a single person to take, since most of the time, you pay for 2. You can get deals where the single supplement is reduced or waived, and quite often those are in less than ideal times of year or on older ships. Of course, less than ideal is subjective. If you have a buddy to go with, it will probably be a better time, plus you right away have someone to hang with while you try to meet others. Most cruises do have functions for singles.

Not going to find many all inclusive options, unless you look at the luxury lines. Carnival has a beverage program called Cheers, which costs $50 per person per day, and everyone over 21 in a cabin must purchase it if anyone wants it. It's not all you can drink, but it covers 15 drinks per day, plus free soft drinks. 7 drinks a day basically is the break even point on this.