Much of the Greek charter fleet is based in the area mostly at Alimos marina (Kalamaki)
Flights to and from Athens are numerous and good value. Getting to the departure marina is easy and quick.
Enormous selection of charter yachts
Two attractive itineraries for a one week cruise
You must cross shipping channel at start and finish (tiresome)
Crowded with other charterers less competent than you!
They are 6 night/7 day itineraries that with thought can be combined into 14 day cruises. If you have that long, consider the Southern Itinerary and continue south down the quieter East Coast of the Peloponnese.
Nisiros is visited by those on their way to the Cyclades, and by those drawn by the sights of the island itself. It has an active vulcano and you can walk down into the crater and listen to the bubbling. There are sulphur vents everywhere. The little village of Emporios is charming, has two good cafe/restaurants and great views down over the crater. The island capital, Mandraki, is over-run by hordes from Kos during the day, but has houses hanging over the sea that rival "Little Venice" in Mykonos. Do go. Recommended establishments in the Services section.