While Greece appears to be small on the map every location change essentially takes a minimum of half a day and sometimes most of the day. While your plan can work it will be exhausting and at the end you will have nothing much more than a drive by experience Bottom line your plan has too many hops and minimal quality time.
Here is what I would do. After a transatlantic flight you will be tired, I can understand why you want to rest for two days in Athens to get over jet lag. If your flight gets in before 2pm in the afternoon I would suggest you load up on Coffee and adrenaline, rent your car and drive to Nafplio. It is two hours of driving. Spend those two recovery nights in Nafplio. It is a charming seaside town with a beautiful waterfront promenade, old town and Venetian era Castles. It is perfect for getting over jet lag.
Nafplio and Peloponnese http://www.flickr.com/photos/stanbr54/sets/72157632094108982/
I suggest you drop Athens on arrival is because it is a foreign experience. It is hot noisy, dusty and full of hustle and bustle. It is not the place to have your first Greek experience while jet lagged.
Nafplio is also centrally located for day trips to the treasure trove of nearby antiquities like Mycenaea, Tiyrns, Epidavros and Corinth.
I would propose you spend three nights in Nafplio for these sites.
If your flight gets arrives in the morning you will have time and energy to do a stop at Corinth to visit the canal and one of Ancient Corinth or ancient Nemia a small version of Olympia with a stadium, temple and a museum. Images of these sites are in the attached album.
Now head to Mystras. It will be about a two hour drive. It takes at least 4 hours to do the site properly. If you get out early enough you can do Mystras and then drive to Olympia. Overnight there.
Here is the major change I am proposing. Since you will be visiting several islands later in the trip, consider dropping Zakynthos. While ferry hopping sounds great it is actually a huge waste of time. The hops from Santorini to Naxos to Mykonos will prove that to you. In my opinion the time you save here can give you an opportunity to explore Greece in a more in depth way.
After Olympia drive to Patras and cross the Gulf of Corinth and go to Delphi. Time your arrival for late afternoon. Find a hotel and then visit the museum. That will prime you for the site next morning. Get to the site at opening which will give you two hours before the tour buses arrive. By then you will be at the top which will give you an extra hour before the crowds are a problem. Depart Delphi and drive to Meteora.
Time your arrival around 5pm. By then all the tour buses will be gone. You will be able to drive up to the monasteries and get photos to your hearts content and have an opportunity to have the place essentially to yourselves. Find a hotel in the village of Kastraki nestled at the foot of the mountains. Next morning visit the monasteries. There are only a few of them open each day so you evening scouting trip will allow you to plan where you want to go. Once the tour buses arrive the place is just jammed. We counted 30 tour buses in the parking lot of one of the monasteries.
Olympia Delphi Meteora https://www.flickr.com/photos/stanbr54/se
We chose to spend a second night in Kastraki and depart the next morning but you may wish to head to Athens then. It is a 4 to 5 hour drive to the airport but it is all on major split lane highways (tolls)
Fly to Santorini.
follow your plan for Santoirni Naxos and Mykonos. Fly or ferry back to Athens and do Athens at the end of your trip. You will be fully acclimatized to Greece by then and Athens makes a great end of trip experience. You can easily spend three nights in Athens and you won't have time to visit all of these sites.
More Island thoughts next post.