Suggestions for itinerary May

Late May is still off season so you should find places to go to at much lower prices than High Season (July/August). Since you arrive so late on your first day your best option is to stay in Athens and then decide whether to spend another day there or head to another destination. However, since think it's best to continue to your destination. Depends on how tired you are and whether you need to catch your breath before continuing onward.

Since May 20 will be lost to travel and the 31 also leaves you 10 days in Greece.

You can split it up between Athens and 1 or 2 islands. Lots of options on islands especially some of the closer ones to the mainland that you can get to via ferry and not waste a lot of time traveling via ferry to more distant islands.

The Cyclades Island group is very popular with a number of very good options. Don't overlook Aegina which is very close to the mainland and has most everything one goes to a Greek Island for without the partying and nightlife and expense of the Big Name Islands. You can combine it with Agistri which is known for it's wonderful beaches.

I can recommend Sifnos, Milos, Naxos, Paros as good choices that won't take a lot of time to get to.

Most people leave Athens till the end of their trip but since you arrive so late you may have to sacrifice the first night in Athens then head out the next morning and return at least 1 day before your flight back home.

Athens deserves at least 3 days to fully experience what the city has to offer.

Check out this wonderful website for everything about Greece, do your research, and make a decision that works for you. Don't hesitate to ask more questions about island destinations:

https://www.greektravel.com/

In addition don't overlook the Peloponnese, especially Nafplio which is one of Greece's loveliest towns and a great place to base yourself to explore World-Class archeological sites and other areas nearby.

You can get overwhelmed with what to do in Greece!

Peb,

You can save the additional days toward the end of the trip to tour Athens. After first night,
go to Peloponnese peninsula and explore that region. It is lovely. Start in the town of Naplio and rent car to visit sights such as Epidavros, Mycenae and cities like Kastro, Kalamata, Stoupa, and Monemvasia..

With only 10 days total, taking ferries everywhere is a "time luxury" you cannot afford. A ferry from Piraeus to Naxos or Paros will take 4.5-6 hours (and that doesn't count the time spent to get to the port wait for ferry, or time getting off)... it could eat up an entire day. Best strategy is to fly out EARLY on May 21. SInce u get in at 9pm, a wonderful ploy is to book into Hotel Avra in nearby Rafina. It has a free shuttle (25 mins ride) to/from Airport IF (and only if) you request it at time of booking. Thus, you could be at hotel by 10:30 latest ... and have free transport back to Airport in the AM to get a flight to 1st island... for most isles the 1st flight of day is quite reasonable price. On May 21, 9:25 am Aegean flight to NAXOS is €82 & you're there at 10:10... you could be in your swimsuit and in the sea by 11 am!! You could enjoy 4 days there (use 1 day for a day-excursion to Santorini if its Famous Caldera View is a Must-see, but don't stay, the cruise-crowds will be massive), then perhaps hop on a fast-ferry to a 2nd Island just for 2 days, then evening ferry back to Athens for final 3 days.

Thank you, these are great ideas to get me started!

While flying is quicker to get to an island destination the OP didn't ask for that which is why I recommended a ferry. If you really want to get to an island combination quickly then Aegina/Agistri would be ideal. The regular ferry takes about 1-1/2 hours or you can take the Flying Dolphin in about 40 minutes to Aegina. Since Agistri is less than 15 minutes away from Aegina via ferry it would make a nice combination.

Check out Aegina and Agistri here:

https://www.aeginagreece.com/aegina-island/

https://www.agistrigreece.com/

You can then get back to Athens in a short time and enjoy everything Athens has to offer.

If you decide to fly then Naxos would be a wonderful choice since it's the largest of the Cyclades with a host of options to experience and enjoy. You can do day trips/cruises to Delos/Mykonos or if you really want to see Santorini that's possible also without having to stay and pay the high prices and deal with the hordes of tourists.

I know how overwhelming it is to plan a Greece trip--it's part of the reason I am only now getting around to going, also in May.
I had read a lot though, and based on how much my husband and I enjoy nature and driving around small town Italy, we decided to head to the Peloponnese, giving Athens really minimal time (we know we are most likely to return to ATH for a second Greece trip). So, you might ponder what it is you want to see and how you want to get around to help flesh out the trip. To me, that amount of time would be enough for two islands max. Have you identified the islands you most want to see?

This is what I've come up with so far, based on suggestions and some research of my own:

arrive in Athens, spend the night
head out to Piraeus in the morning and take slow ferry to Aegina
stay in Aegina Mon - Fri, possibly day trip to Angistri, leave Fri ferry back to Athens
rent car in Athens and drive to Nafplion
stay in Nafplion 2 full days, drive back to Athens and turn in rental car on 3rd day
spend rest of day plus next 3 full days in Athens.

You're getting there, that is better... I would have some "tweaks" to offer:

• Think strategically about hotel for that first night -- you'll be going to Pireaus in the AM, and be aware that the first "slow ferry" is 8:40, and there's not another till about noon. If you plan to taxi to Pireaus (€25) ;you can stay anywhere but if you want to take the Metro (Green line-- €1.8) the station in Central ATH is MONASTIRAKI (see map; click to enlarge) - https://www.in2greece.com/mappages/athens-metro-map.jpg You'll be pulling your rollng bags, so good idea to find a hotel for that ONE night nearby... Attalos is one that people mention.

• TIME-DiVIDING -- I'd suggest take at least 1 day off Aegina, and add it to Nafplion -- SO much more to do/see there -- and it will have an island vibe, because it's surrounded by water, and numerous beaches; when I'm there I swim every day (the cute Town beach, Tolo, and my favorite, Asine). I trust you already have consulted http://www.visitnafplio.com/ -- I implore you to open EVERY link ... its knowledgeable creator/editor has SO many walks & trails to share!

• EFFICIENCY -- I trust you hav thought about your route to/from ATH Airport & Nafplio ... on the OUtbound , it's good to go over the Corinth Canal, and Stop atANCIENT NEMEA briefly on NORTH side of big highway -- it's just before the exit on SOUTH side to go to Nafplio. During your time in that town u can go see Mycenae, TIryns and or Asine if so inclined. On that final day, driving BACK toward Athens, it's efficient at outset to drive up BACK road to Palamidi for a quick look & picture-taking.... then take the road "across the thumb" of that Peloponnese to get to EPIDAURUS in the AM. Then take the Coast road up to Isthmus, where u can stop to get a good look at the Corinth canal, and THEN hop onto the "big highway" to head back to Airport. This loop avoids excessive backtracking.