Oct 2023 first time in Greece

Googling the ferries, it looks as though they move onto the reduced winter timetable around 7 October. Some of your routes only seem to operate in the late afternoon and there is only one boat a day. There is more flexibility in late September.

The sea should be warm enough for swimming, particularly in September and early October. I have had very mixed weather in mid October in Greece.

If you see good flight prices, take them. Otherwise monitor them such as on Skyscanner.

Thanks, Jennifer. You found more on the ferry schedules than I did. I’m thinking I should move our trip up a few weeks. Something to consider.

1/ You have "chosen" the most visited Greek islands, it's your right but I don't think this is a choice made independently.
Maybe like 95% of first-time travelers to the Greek islands, you blindly follow the recommendations of tour operators and tourism marketing in general. Seen Youtube videos, photos from instagrammers, etc.

On the other hand, YouTube channels like this one, from an American living in Athens, can be more informative:

https://www.youtube.com/@agirlandherpassport/videos

This one can be particularly interesting for a first visit:
https://www.youtube.com/watch?v=h2UhRv_xDog

2/ The consequence of the first remark is that even at the end of September there will still be a lot of tourists, mainly in Mykonos and Santorini which are, in addition, cruise destinations. Don't expect to be in a quiet environment.

3/ Mykonos is a well-known island for partying in a gay friendly environment. It is very popular with the international jet-set who come here to enjoy cocktails and listen to famous DJs in the many nightclubs on the island.
If that's not what you're looking for and you only want to see white and blue houses and windmills, forget Mykonos. White and blue houses and windmills, you will see them everywhere else in the Cyclades.

4/ Naxos has become a very popular island with North American customers, probably thanks to the Rick Steeves promotion in recent years. (Rick Steeves has not been to many other islands)
But it remains very frequentable and a good example of a Cycladic island.

Paros is also very popular, but more by a European clientele.

Anyway in Naxos and Paros you will find what makes the reputation of the Cyclades. The beaches, the small blue and white villages, archaeological sites, taverns, and still some goats on the roads :))

5/ Be careful not to be too greedy in islands to visit, travel from island to island is extremely time-consuming. It's at least half a day and almost a day for each trip.

6/ The weather at the end of September and October will be perfect for visiting the islands, even swimming, but it can also sometimes be a problem to take the ferry. It is not unusual for all ferries to be canceled for a day or even two due to too strong winds. It happened at least 3 or 4 times this year in the September/October period.
In September 2019 it was 3 1/2 days without any ferry in September.
For my part, it only happened to me 4 or 5 times in 25 years of traveling by ferry in Greece, which is a good score. :))

7/ The advice when you arrive from a transatlantic flight in Athens and want to go to an island that has an airport is, when it is possible in terms of schedules, to stay in Athens only for a layover at the airport.
If you want to visit Athens you can do so at the end of your stay when returning from the islands.
Keeping Athens for the end also allows you to have a safety margin in case of weather problems. (see point 6)

That said, about the ferries:

Complete ferries timetables for September will not be published until March/April. It's normal not to see them right now.

At the end of September, for Mykonos you will have 4 to 5 ferries per day from the port of Rafina and 2 to 3 per day from the port of Piraeus.
From Mykonos to Paros: 2 to 3 ferries per day.
From Mykonos to Naxos: 5 to 6 ferries per day.
From mid October there are slightly fewer ferries but still daily ferries.
Naxos-Santorini will still be served by 4-5 ferries per day.

From March April 2023 you will be able to consult them on several websites including this one for example:

https://www.ferryhopper.com/en/

Naxos has become a very popular island with North American customers, probably thanks to the Rick Steeves promotion in recent years.

Rick Steves does not write about Naxos on his website or in his books. The Greece forum is dominated by a few people who’ve been to Naxos and like it.
One of the best islands for swimming in Oct is Rhodes and is an island the locals recommend. I've never known anyone not to like Rhodes.

Rick Steves does not write about Naxos on his website or in his books

Damn! I'm sorry, I hope he won't mind too much.
I'll have to find someone else to blame now :))

You will find a lot of information about the Cyclades on this forum. We were fortunate to receive our best information from Janet & stanbr from this forum. We spent the month of September 2017 in Greece. We spent a week on Naxos and 4 nights on Santorini. Naxos by far was our favorite island for the “real Greece experience.” Congratulations on your upcoming anniversary and enjoy your planning. See blog on this posting: https://community.ricksteves.com/travel-forum/greece/car-needed-in-naxos

Thank you, Janis. Yes, Stanbr & I both admit to being Naxophiles --- but neither of us were influenced by Websites, videos or travel agencies. When each of us started, (me back in 99, and I think stanbr & spouse in '98 or 97), there was not even an Internet OR Steves Tours! We each researched the old-fashioned way... with guidebooks, way back when these were full of descriptions, not color photos. I landed on Naxos that year, planning to stay 3 days... and kept postponing my departure 3 times! I was on my own, but found friendly locals & other travelers everywhere... I've been back 13 times! Of course I go to many other islands and mainland favorites --- but Naxos is the one constant. I met stanbr & his missus there & we've rendezvous'd often.

Much has changed, of course, as more people discover the place -- and it IS most enjoyable when you can go in May or Early June, or in September... times that are perfect for swims, walks, sunsets, discoveries. Because the harbor does not accommodate those monster cruise ships (Naxians turned down an offer to have it dredged deeper) and the airport so far has runways too short for jets, Naxos has not yet been overwhelmed by cruise armies or package-tour mobs. I do urge you, go now before "progress" could occur. But please -- don't just make your choices by flipping thru pretty-photo promotional websites. Go to your library; pick up Rough Guide, Lonely Planet, Cadogan guide to Isles. Read about all the islands, written by people who know & love them, not marketers. It's worth it for a memorable 40th.

Thank you all for great advice and suggestions. Ironically, I watched a few “girl and her passport” videos to start planning. We’ll be flying to Mykenos from Athens for convenience and staying just two nights. Then ferry hopping to Paros and Naxos for 5 nights each. Another ferry to Santorini for several nights, then fly back to Athens. On Santorini we’re staying at Athermi Suites, hopefully avoiding the worst of Oia and Fira crowds. Before flying back to the States, a night or two near Athens…..I want to visit the Poseidon temple site. At this point we’re still flexible as far as dates ( seriously thinking we should move trip to the end of September) but want to stay in the Cyclades for this trip.

Great thread.
September is a good time to visit the Cyclades. The crowds are thinning as Europeans have finished their holidays. The weather is still good and the sea is as warm as it is going to be.
Have a great time.

Here are some bonus images of Naxos
Around Naxos town 2022 https://www.flickr.com/photos/stanbr54/albums/72177720299959098
Back to Naxos 2022 https://www.flickr.com/photos/stanbr54/albums/72177720299940917

Trip around Naxos https://www.flickr.com/photos/stanbr54/albums/72157634605629689

stanbr your photos are gorgeous! We have decided to move our itinerary to mid September. At the moment we have 18 days, but just might extend it to three weeks to spend longer on Paros & Naxos. More planning, but that’s part of the fun!!

Thank you for your kind words. I love taking photos in Greece particularly Naxos.