Considering your interests (great food, hiking, beaches, nightlife unimportant) then Naxos should definitely be your other island. (And Naxos has many daily ferry connections with both Santorini and Athens.) Also, Athens needs at least one full day to explore so you should drop any thoughts about Delphi or Nafplio. Also, I would look into flights from Athens to Santorini on your night of arrival. If you could get to Santorini that night (and move your day in Athens to the end of your trip) you’d almost gain an entire day and could spend two nights on Naxos.
Nine weeks in Greece is a dream itinerary it certainly gives you lots of flexibility. As you seem to have Athens and the Peloponnese sorted, you just need to sort out your five weeks on the islands. What you need to realize, however, is that the islands are not all mutually interconnected, but rather they are ‘grouped’ – both administratively and from the point of view of transport routes. Here are the main groups.
Fiji is poised for a comeback after 2016’s Tropical Cyclone Winston, the most severe on record. The quintessential Fijian Jean-Michel Cousteau Resort on Savusavu Bay reopened in September with 25 newly thatched houses known as bures. For total seclusion, guests are ferried via seaplane to the remote Kokomo Island, a new collection of 21 bures and five villas on uninhabited Yaukuve Island.
The busiest and hottest months. If you like beach parties and packed clubs then Mykonos is the place to be. The less-busy islands (Antiparos, Sifnos, Ikaria, Folegandros, Milos) have short tourists seasons and this is when they’re fully open and running. Santorini, Crete, Rhodes, and Corfu are in peak-season but all are large enough to retain their charm.
Major airlines dominated their routes through aggressive pricing and additional capacity offerings, often swamping new start-ups. In the place of high barriers to entry imposed by regulation, the major airlines implemented an equally high barrier called loss leader pricing. In this strategy an already established and dominant airline stomps out its competition by lowering airfares on specific routes, below the cost of operating on it, choking out any chance a start-up airline may have. The industry side effect is an overall drop in revenue and service quality. Since deregulation in 1978 the average domestic ticket price has dropped by 40%. So has airline employee pay. By incurring massive losses, the airlines of the USA now rely upon a scourge of cyclical Chapter 11 bankruptcy proceedings to continue doing business. America West Airlines (which has since merged with US Airways) remained a significant survivor from this new entrant era, as dozens, even hundreds, have gone under.