"The best of both worlds" is to have the best aspects of one choice and the best aspects of another choice when you have been asked to select between two choices. Example: "You can either get up early tomorrow and get a lot of work done, or you can stay out late tonight and have fun with your friends, but you can't have the best of both worlds." Often we cannot, but sometimes we find a way to have "the best of both worlds,". Example: "My wife and I bought one house in Paris and one in New York; it gives us the best of both worlds."