In an official folder concerning the Cyclades, you can find the following statement about Koufonissi: “have beautiful, sandy beaches, sparkling clear sea and palm trees”. These word appeal to me, and since I’m looking for peaceful islands Koufonissi is a good choice.
I never been on Koufonissi since then, but I have been at the little port (onboard ferries) a couple of times, and in June the island seems to be packed with Scandinavian families. A lof of development has also taken place during the last decade, so the island is not tranquil anymore, especially during the main season. Well, during spring and autumn I think you can have the island “on your own”.