Honeymooning in the Cyclades mid June

We have been to Syros which is the administrative capital of the Cyclades. It was not a tourist center,
although , of course, there were some tourists. Not bad, but not special. I have read good things about Tinos, very popular with Greek locals. Hopefully, some posters who have been to the other islands you list can chime in.
Best wishes on your upcoming honeymoon.

Milos and Naxos would be lovely!

Here are, in order, the most frequented islands of the Cyclades, so theoretically the ones you want to avoid:

Santorini, Mykonos, Naxos, Paros, Milos.

In fact, if there is an airport, there are more people.

Santorini and Mykonos also receiving cruise ship visitors are the big winners in terms of crowds

That being said, before June 20 you won't have too many people in Naxos, Paros and Milos.

Sifnos is not a sprawling island, you must confuse it with another island (and I wonder which one!)

If the hiking trails in Sifnos are excellent, Sifnos is also an island that can suit you even if you don't like to walk. It has everything that can make the typical postcard of the Cyclades with more authenticity compared to Santorini for example.
It is also renowned for its cuisine (and its pottery).

The same goes for Tinos which is even quieter than Sifnos but has fewer beaches, less known cuisine and almost no pottery but is full of beautiful typical villages.

Syros is the capital of the Cyclades and has its charm, however it is not typically Cycladic in style, no white houses and blue domed churches.

Know that having a rental car is also a parameter to take into account. Some islands are more or less well served by local buses.

Naxos, Paros and Sifnos have a good bus network. That of Tinos and Milos is much less efficient (especially in June)

The Naxos-Paros-Sifnos trio is also the one with the most beautiful sandy beaches.

Do not plan anything without having seen the ferry possibilities.
To know them see on ferryhopper

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

or on openseas.gr

http://www.openseas.gr/

(same information but with different presentations)

And if you are looking above all for calm and authenticity, see also Serifos, Kimolos, Folegandros and Amorgos

@JoLui -- syros was the sprawling one, not sifnos :)

funny, after I posted this I was thinking of doing:

Tinos -- heard the food scene is wonderful
Naxos -- for the culture/agriculture
Milos -- everyone says the beaches are wonderful

And it would be pretty easy to do Tinos --> Naxos --> Milos with the ferries I have looked at (don't have exact dates yet)

Would this be unwise re Milos/Tinos at this time of year? We know it is a bit before tourist season (our wedding is June 4 but we would probably leave the following week, around June 11) and we would be open to renting a car, though we would prefer to use public transit.

Argh, sorry I thought you were talking about Sifnos. It's my fault (brain damage)

With 10 days I don't recommend going to more than 2 islands, even not counting the arrival and departure days.

Going from one island to another is very time-consuming and you will spend your time packing and unpacking, transfers between accommodation and ports, and ferry crossings.

Also take into account that it is safer to return to Athens at least 1 or 2 days before the day of your return flight. Bad weather, ferry breakdowns or sailor strikes could get you stuck on an island while your plane takes off. Considering the price that a "no show" would cost you with a missed Athens → Home flight, a margin of safety is always preferable.
And it would be a shame to end a honeymoon this way. :))

Note that Tinos is very easily reachable by ferry from the port of Rafina, instead of Piraeus. The port of Rafina is located 20 minutes from Athens airport. If you have a flight that arrives early enough you can take a ferry at 2:50 p.m. or 5:30 p.m or stay overnight in Rafina and catch the first ferry the next morning. (the Avra Hotel in Rafina has a free shuttle from/to the airport)

Also be careful if you want to add Milos to Tinos and Naxos.
Milos is in the Western Cyclades, the ferry routes are specific and the Naxo-Milos connection less frequent, provided only by uncomfortable and very expensive Seajet Catamarans which arrive in Milos after 9 p.m.

One thing is sure, you will need a car if you want to enjoy Tinos and Milos in June. It will also be useful in Naxos although less problematic if you stay near Naxos Town.

Finally, don't wait to finalize your trip, even in June plenty of accommodation are already booked (especially in Naxos and Milos)

Just to add to Jo Lui advice the more hops you take the less time you have on your chosen islands.

Rather then hopping to several islands why not choose one for a week and really get to know that island. On your list Naxos is the one island where you get all your wants. Naxos town has a lovely waterfront promenade, an old town with a maze of back alleys leading up to the fortified Venetian era Kastro. The 6th century BC Portera stands guard over the harbour. The interior is mountainous with villages and hiking. Naxos has some great beaches good sand, On the south coast there is about 5 kilometers of a string of beaches. There are some antiquities and good hiking as well.

There will be lots of tourists but Naxos is so large that it absorbs them so does not feel crowded. Naxos town at sunset will be the busiest place but still not overcrowded.

Plaka beach may give you what you are looking for. The further out you go at Plaka the less people go that far.

Perhaps I can tempt you

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

Plaka beach https://www.flickr.com/photos/stanbr54/albums/72177720299954668

I was starting to worry about not reading stanbr's recommendations about Naxos.

Phew! he is fine!

LOL!

JoLui I think I am becoming too predictable! Gotta love Naxos though.

Please avoid Ios. This is party central for the young and drunk.

We will avoid Ios, do not worry!

We were leaning Milos over Naxos because of the unusual beaches, but it seems it may be hard to access them in June. Naxos is easier to get to from Tinos if we decided to hit up two...

ug every time i read a compare and contrast though it brings me back to Milos > Naxos. I keep hearing amazing things about the food in Tinos which is why i was thinking Tinos and Milos but it's not that easy to go between them (unless we go to Naxos!)

Now I am thinking Sifnos--> Milos??
Damn, wish we had infinite time

Sifnos and Milos are much easier to associate when it comes to finding ferry routes.
In addition to the expensive fast Seajets the two islands are served from Piraeus by the traditional ferries Zante Ferries, Aegean Sea Lines and Hellenic Seaways.

Consider pairing Naxos and Amorgos. You could spend most of your time on Naxos (5 nights?) and then it’s a short ferry to nearby Amorgos (3 nights) for a totally different experience, and then back to Athens for 2 nights.

Amorgos has two ports. We stayed in Katapola, the main port, and loved it. Others like Aegiali, which is more like a resort, with a better beach. The main attraction on this little island is the Hozoviotissa Monastery, carved out of a cliff face. Good food, beautiful views, peaceful surroundings, very few tourists.