What is the best itinerary in terms of islands?
This depends on what islands you want to visit and how much time you have. But the best plan is to do a one-way charter. So for example if you were going to visit the Cyclades and you had a week you would go Kea, Kythnos, Sifnos, Paros, Naxos, Mykonos, and end up on Syros. You don’t have to backtrack to return the boat to the port you started at so you can see more islands. Many people who do this end up on an island that has ferry connections to Santorini which is a long trip by sailboat but no big deal by ferry. So they do their charter and then spend a few days on Santorini and then take the ferry, highspeed or fly back to Athens. Or they spend a couple days on the last island where they left the boat. As for picking which islands to visit you can visit Matt’s Greek Island Guide but it will also depend on the wind and anything you plan is subject to change. For example if you have to sail against the wind to get to one island you might decide to go to another that will be easier. An