If you want to see the islands of Greece, do travel light. Start in Pireaus and take a ferry to Aegina. Stay in a room or a small hotel. Do not reserve but fix it on arrival. Stay as long as you want and move on to the next island by ferry. If you are not on a sailboat, that is the best way to experience the Greek islands and the "Mama Mia and Zorbas the Greek" feeling. Do not take a cruise.