What exactly do you mean by "freestyle"? "Anytime dining"? There are a number of cruise lines that offer this, with varying degrees of success. Norwegian uses "Freestyle Cruising" as their tag line. Princess and Royal Caribbean also have their own versions of anytime dining.
As for destinations, where do you want to go? Caribbean? Alaska? Europe? South America? Cruises can give you a taste of various places in all of those destinations. But since you haven't indicated what your interests are, there's no way to make constructive suggestions.