2 week Greece itinerary in August

Since you're spending a lot of time in Athens, why not take a day trip to Hydra. If you have a car, you can take another day trip to Nafplio.
I would take Crete off the itinerary because you’re not allowing enough time to see it. I would also replace Mykonos with Rhodes.

I would make an effort to reach your first island destination on Day 1 rather than splitting your time in Athens, thereby wasting a significant portion of your last full day in Greece as you travel back to the city. Whether that's a viable option will depend on flights available to you, but I know some people have been able to pull it off.

Two nights at a destination is only one full day and however many hours remain after you take a flight (annoying) or a ferry (potentially slow). Two Cycladic Islands for two nights each isn't the way I'd go. I'd give up a potential day-trip to allow for a third island night, and I wouldn't choose Mykonos at all, which is a hyper-touristy place. I preferred Naxos.

I agree with MaryPat that Crete is not a good choice when you have only 3 nights. I love it, but it needs considerably more time than that. You could drop Mykonos and shift both those nights to Crete, which would give you a better look at the latter.

Our trip in April 2018 had the opposite Athens schedule, for what that’s worth. Because we landed at night, and reached our Athens one-night hotel (Rick-Steves-recommended Peri’s) about 8:45 PM, we had just enough time to have the hotel order us a delivered dinner (excellent) from the restaurant down the street before they closed, and polish it off before collapsing in bed for the night. The next day, Peri’s took us to the Piraeus port, and we were scheduled to catch the earliest ferry to Hydra, but rough seas canceled that sailing, as well as the next one, so we shared a taxi with another couple to reach another port that offered calmer waters. After we had time on Hydra, and the bulk of our trip touring the Peloponnese and the Delphi area, we finished up in Athens for several nights.

Our fall 2019 trip was only Crete for 2 weeks. If you have just the 3 nights, you’ll probably need to stick to the north shore of western Crete, although the eastern half of Crete has so much to see and do. Are you interested in ancient Minoan sights, or there for the beach? We slept in several towns, and you might be looking at one place for 3 nights, or a couple nights one place and a single one-night stand. Either would give you a bit of time for that island. We picked up our rental car at the Iraklio airport, and returned it by the old port in Hania, where they collected the car. Driving within either town will be a challenge. Hope your trip can be done and that you enjoy Greece!

I love Mykonos and would generally keep it on your itinerary if the unique things Mykonos has to offer are important to you (nightlife, fancy restaurants, party beaches). You may also want to consider Milos while you are in the Cyclades - it is absolutely stunning. Crete is huge, and it may be overwhelming to try to see much of it in 3 days, but if you're okay with focusing on one part of the island it is certainly not a bad choice.

I agree with others up thread to eliminate Crete. It needs more time. We had 4 nights in Athens when starting our RS Greece Tour. After the tour we spent 6 nights on Naxos. It was our favorite island. We felt it was authentic Greece. We also stayed 4 nights in Santorini. We thought 3 nights would have been enough. We enjoyed a day tour in Santorini that included the Akrotiri excavation site. Well worth the time in Santorini. We visited Greece in the month of September. It was warm, but tolerable to us.

I think 2 nights would be sufficient IF you arrived in the morning of the first day and/or departed the afternoon of the departure day so that you have what amounts to 2 full days. We stayed on Santorini for 3 nights/2.5 days and I thought less time would have been better (just two). Loved Crete, and you could certainly visit Chania, OR Heraklion for those 3 days but not venture out much beyond that (maybe a beach/ruins day). I dont have an opinion about when you stay in Athens, except that, if you keep the current plan, you might want to try to stay at Peri's or similar rather than commute back into the city (30 minutes) from the airport and then back the next day for your departure

I would also shorten the route and concentrate only on the most important things

I also think you're trying to fit in too many places. You'll be spending too much time getting from island to island. The airport in Heraklion is not far (by taxi) from the city center, but it's a big city with little to recommend it unless you are very interested in ancient Greece. I spent 5 delightful days in Chania, but it's a long drive and expensive drive from the airport or a cheap but possibly very long trip by bus. Between Santorini and Crete, there are jet ferries - the journey is about 2 hours, but the ferry only goes to Heraklion. I don't know if there are flights between Mykonos and Santorini. The ferry is about 4 hours and it can take a long time to get from the port in Santorini to the town when the crowds leave the ferry.

I agree with acraven, Naxos is wonderful and well worth 2-3 nights. The ferry port is a short walk from the center of town and the beaches are great.

It takes a lot longer than you think to move from island to island. You lose a lot of time in travel. I would not stay less than three nights on an island.

I also would consider flying to your first island upon arrival and save Athens for the end. We flew from Athens to Santorini, stayed three nights, and then ferried to Naxos stayed four nights, and flew back to Athens. We really enjoyed this routing and would highly recommend. Santorini is very touristy but was visually spectacular. Naxos has a bit of everything-beaches, towns, mountains, historical sites.

I would also fly back and forth, it's easier

I would also save Athens for the end. We did a trip very similar to Beth’s in 2019: flew into Athens then flew directly to Santorini for 3 nights; took the ferry to Naxos for another 3 nights, then flew to Athens for another 3 nights. Santorini is gorgeous, especially if you stay at lodgings that offer a view of the caldera. Totally worth the extra expense to be able to have breakfast on a terrace in the early morning or a glass of wine in the evening overlooking the beautiful caldera. PM me if you’d like some hotel suggestions. Naxos was wonderful on all counts, especially the food. If you’re as young as our children (early 30’s), you’d probably want to visit Mykonos. On the ferry over to Naxos, they were researching the ferry schedule to Mykonos for a day trip but it didn’t work out as the ferries don’t run late at night. As far as saving a stay in Athens at the tail end of your trip, I had read in this forum that you want to give yourself some wiggle room at the end of the trip in case of flight delays or cancellations since you wouldn’t want to miss your flight back home. Have a wonderful trip! We hope to make it back to Greece in late summer as well! Fingers crossed!

Thanks all. Very helpful!