Which greek island is beautiful, fun, young and also relaxing without being trashy
Region: Southern Aegean
All the islands are wonderful
I would suggest probably Corfu, or one of the islands on the Ionian side. There is of course Skiathos, or Kefalonia, or even Limnos. All the islands are beautiful, but you should try to pick one of the islands that is a little more low key. That way you'll have some night life, beauty and relaxation. You might also want to consider mainland Greece, but no the main city. Parga, even Thessaloniki is really nice. It is the city, but it is not as touristic as Athens, easy accessible, much to do, and relaxing.