As a starter to explore ferry services, go to the Ferryhopper.com and punch in your route searches. Note: air travel between islands is not generally good. Air travel is normally only feasible between Athens (or other mainland destinations) and the island in question. Some exceptions do exist – Rhodes Kastellorizo, Kos-Leros-Astypalaia, Thessaloniki-Limnos-Ikaria etc. but again you will need bookings weeks in advance.
The almighty church has kept nightlife in check. If you must see and be seen, head to quietly glamorous Astivi or Stoa bar, on miniature Agia Lesvias square, in Hora. Beach life is generally languid and low-key; Psili Ammos and Livadi Geranou are our favourite hideouts. Dinner reservations are essential at Benetos, for Med-Asian fusion on an organic farm, and Lambi for grilled fish on a purple pebble beach.