From July 15 to 22, Clara and I traveled aboard the 45-passenger mega-yacht cruise ship, Harmony V, though the Greek Islands.
We were lucky in that the recent civil unrest had briefly abated, but believe me, everyone from tour guide to taxi driver had something to say about the economic crisis.
We began in Athens, where we toured with our friends through the gay area of Gazi.  The next day, we visited the Acropolis, the Dionysus Theatre, and the Acropolis Museum, shopped endlessly, and had dinner in the Plaka.  Yes, we napped and did not dine till late.  And, it was HOT.  Before leaving for our cruise, we swam and relaxed on the rooftop pool of the Marriot Ledra, with the Acropolis in the background.
We've never been on a cruise before, so we were nervous and did not know what to expect.  The yacht was lovely, the room was fine, and the food was very good. Some things were better on the boat, like the fish, surprisingly. The service was excellent and there were enough people so you could find someone nice to talk to. We visited the islands of Kea, Delos, Mykonos, Santorini, Crete, Kythera, Nafplion, Monavassa, Hydra and Poros.  No, we didn't ride the donkeys up in Santorini, but the cable car was scary.  The cruise also made two off-shore swim stops along the way.  The water was AMAZING!
We would travel at night; arrive at an island in the morning; eat; take a tour of an archeological site, where the tour guides are supremely well-educated and knowledgeable; pass out cold for a couple of hours and then go out for dinner—lamb! tzatziki!—or to party.   The nights would end with ouzo for me, mojitos for Clara, and perhaps a game of dominos or backgammon on the top deck.
Highlights were many, but we both equally marveled at the level of engineering the Greeks managed 3000 years ago: the running water, cisterns, architecture, measurements and art.  The population of Santorini evacuated before the eruption of the volcano that destroyed a huge part of the island.  They had advance notice.    No one knows where they went.  Perhaps the myth of Atlantis offers an explanation?  However, the population of Minoan Crete wasn't so lucky and they got wiped out by the resulting tsunami.
If you are the type of person who likes to cruise but wants to get off the boat and visit sites, a smaller cruise is the way to go.  Our honeymoon was fabulous!