Help with some cruise lines?

My fiance and I are planning a cruise, just a little 4-5 day getaway. We were looking into Carnival, and really like the pricing. But have heard that there's tons of kids on this particular cruise line. Were planning on going when there wouldn't be a college break. And we were also looking at Royal Caribbean, but I like the ports of call for Carnival better (cayman islands, jamaica and key west). But my question is which cruise line would you recommend and is there a way that you can pay extra to get it all inclusive like for your drinks and everything. Because my fiance and I like to 'enjoy' ourselves with alcoholic beverages lol! And don't really want to be a HUGE bill at the end for the drinks we had! Any feedback is greatly appreciated, thank you!