One place that beats all possible travel suggestions with its unique morphology is my home island Crete. It combines beautiful sea, beaches of a wide range of colors (from pink to black), African rocky landscapes, sand hills, mountains, you name it. It also holds a good 3K of history on its shoulders as the home to the Minoan Civilization (remember Minotaur?). Dead cheap, too. I would recommend Chania town and Elafonisi Beach as first stops.