I think the summer trip that I enjoyed the most was last summer in Greece. I usually do a beach big trip during the summer, and a no beach trip on Easter holidays and another on Christmas holidays.
We started and finished in Athens, it was much more cheaper to go again to Athens at the end of the trip only to take a plane there to Barcelona, than take a plane from an island.
The itinerary was: Athens – Crete – Santorini – Mykonos –Athens.
To move inside Greece, we checked what was cheaper in each case; plane or ferry (ship).
So here the first stop: Athens!