itinerary feedback please (revised itinerary) thanks for help so far!

Direct Ferries is what I used as a consolidator to see what ferries serviced what islands: https://www.directferries.com/global/index.html. All your routes are direct so this itinerary works. Note: Santorini is known as Thira.
Apr 29 - take a bus to Nafplio the day you arrive in Athens since you will return.

Thanks MaryPat. Unfortunately, we arrive in Athens at 8 pm so we thought it best to stay in Athens & explore it rather than trying to get to Nafplio in the late evening.

Hello from Nanaimo.
We make that long transatlantic flight regularly to Visit Greece, Getting over jet lag in Venice sounds pretty appealing.

I might make a couple of suggestions that may make your trip logistically better.
Your plan has you in Athens three times even if one of those times is only to get to Piraeus. Those three trips in and around Athens is a serious use of precious time. Given the time required to commute into Athens many of us here suggest you do Athens last so you only have one trip into and out of Athens.

You may want to consider changing your plan.

On arrival in Athens transfer to Nafplio. You will be over jet lag so a car rental from Athens airport makes sense. Nafplio is a great destination with its fortresses, and lovely old town. On the way to or back from Nafplio be sure to make a stop at Corinth. You can see the canal and then ancient Corinth and not to miss the great fortress at Acrocorinth. It has 360 degree views over the countryside. From Nafplio you might even choose to take a drive to Mystras the last Byzantine city.
Nafplio https://www.flickr.com/photos/stanbr54/albums/72157632094108982
Delphi and Meteora https://www.flickr.com/photos/stanbr54/albums/72157698930270992

Corinth Area. https://www.flickr.com/photos/stanbr54/albums/72157711755443483

Drive back to Athens airport and catch a flight to Santorini.
Chances are you can get a flight for close to the cost of a fast ferry.
Island sequence is important so starting in Santorini makes sense since it is your furthest island.

You do know that every ferry hop eats up half a day because you are at the mercy of the ferry schedules. The more ferry hops you make the less time you have for each destination, You may want to consider dropping one island.

It is still early season so Naxos will not be to busy. I would suggest you find a hotel at St George beach. Its part of Naxos town just a short walk into the waterfront promenade. There are lots of hotel on the beach, Our favourite is Boutique Hotel Glaros. Their breakfast is gourmet.
Naxos originally had a hotel area concentrated at St George beach. Since Naxos has become popular there are a number of resorts being built but most of them are not at St George. Many, while more modern are not as central as St George. Since you are early season St George is a more logical place to stay.

Naxos 2022. https://www.flickr.com/photos/stanbr54/albums/72177720299940917/
Naxos town 2022 https://www.flickr.com/photos/stanbr54/albums/72177720299959098

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

Honestly you need a full week to get to know Naxos .

Get back to Athens by ferry or fly. Cost of the ferry and the flights might be pretty much the same cost.

both Naxos and Paros have airports so you can fly back to Athens at the end of your trip. Athens needs 3 days to do well.

Hope that helps

Agree totally with stanbr, and like him, have done that sequence many times. YOu can get your "ferry Experience" by taking the BLUE STAR ferry (lilke a small liner... 1200-1500 passengers, 3+ decks, with open back decks to sit on & admire views). It leaves at 3:15 pm... nice view of cliffs leaving caldera... 2 hours to Naxos, enjoy view.. llike a "mini-cruise." As he said FLY back to ATH airport (45 mins vs 6-7 hrs on ferry) & buy plane tix early at "promotional" rates, not mch more than a "reserved economy" ferry seat. From airport, calling car service (City Cab or Welcome Pickups) is about €45 flat fee right to your central ATH hotel.

Thanks very much to stanbr (fellow Canuck) and also to janet. We are trying to find a flight from Venice to Athens which arrives in Athens earlier than 8 pm but not having much luck. Have tried Volotea, Lufthansa, Aegean, ITA, Ryanair. Any other suggestions for flights ?

I intended to suggest you fly directly to Santorini from Venice but no connections or timing worked. Even Venice to Athens to Santorini seemed to be awkward which is why I suggested you rearrange your trip and go to Nafplio first. the rest of your trip works logistically better with the adjustment i suggested,

Several important things to consider:

You will be in Greece during the Orthodox Easter celebrations (from Holy Tuesday April 30 to Easter Monday May 6).
Which implies:

May 3, 4, 5, and 6 will be public holidays.

There will be many Greeks traveling by cars, buses, trains, ferries to celebrate Easter with their families.

Don’t delay in booking your accommodation

In addition you will also be in Greece on May 1st which is also a public holiday

Don't change your plan by wanting to take a ferry on May 1st. This is the day when ferries are traditionally on strike.

Your Volotea flight arriving at 8:20 p.m., it will be too late to take a flight to Paros or Naxos.
Personally, I would have taken the Aegean flight A3671 even if it arrives a little later at 9:55 p.m.

Why?

1/ Because Volotea is a Spanish budget company with which I have already had some problems (and not just once)

2/ Volotea flights arrive at the Athens satellite terminal dedicated to low cost flights. From this terminal you will have about an additional 20 minutes walk to reach the main airport building.

3/ Volotea base fares seem cheaper but they do not include seat selection, cabin baggage or checked baggage
If you want all of that, you will pay more than the Aegan ComfortFlex rate.

Whether you take the Volotea or the Aegean, don't waste a night in Athens to go by bus (or rental car) to Nafplio the next day. Save the visit to Athens and Nafplio for the end of your stay.
Do like all travelers accustomed to Greece and trips to the islands, on April 29 book a room in a hotel at the port of Piraeus and take the Blue Star Delos at 7:30 a.m. for Paros the next morning.
You will be in Paros before noon.

That being said, going to 4 islands in 2 weeks is way too much.
Each ferry trip takes a good part of the day. You have to check out of the hotel, go to the port, wait for the ferry (which is often late), travel by ferry, arrive at the port and transfer to your accommodation.

So spending 3 nights on an island is actually only 2 full days.

With your schedule only 2 days in Paros and 3 days in Naxos is too short, you will not enjoy your stay on these islands.

Also pay attention to your Naxos→Folegandros and Folegandros→Santorini ferries trips . These are not the usual ferry connections, they are only operated in summer by small Seajets catamarans which are very uncomfortable and expensive (and unreliable in terms of respecting timetables)

I have been to Greece four times in my life and only rented a car once, in 1985.

However, I have taken tours that used the highways (in more recent years).

I would warn you that the highways, particularly the ones from Athens to Corinth and the Peloponnese Peninsula are not that great. Traffic is terrible and very slow.

The best visit that I have had doing some Greek Islands as well as Athens was on a cruise that visited four islands as well as Naphilon. I have talked with people that have taken ferries and understand that the long ferries accommodations are not that wonderful. Also, they are very slow. If you can find a good cruise consider taking it.

Thanks to everyone for all the advice. Traveling around Greece during Easter is sounding a little scary, but we intend to avoid taking any buses, trains, etc. during the Easter weekend. Hopefully, that will make things go smoother. We are also considering dropping Folegandros from our itineray.

Still trying to find a decent flight from Venice to Athens or Santorini. Flying Aegean Air or Volotea (VCE to Athens) involves a night at either Piraeus port or Athens airport, which we would like to avoid. We might end up visiting a cousin near Bergamo & fly from Milan Bergamo to Santorini on RyanAir.

I understand that you want to avoid spending a night in Athens before leaving for the islands. This is also always what I try to plan. but know that a night in Piraeus is not really a wasted night. The atmosphere of the port is quite nice and lively. Don't imagine arriving late in the evening in a deserted place, the Greeks don't have dinner before 9 p.m./9:30 p.m. There are quite a few restaurants and taverns open until 1 a.m. or later

All flights for spring/summer 2024 have been published, it is unlikely that further flights will be planned.

For a Venice→Athens on April 29 you will only have the two direct flights Aegean and Volotea.

There are no other flights to Greece from Venice that day.

With the Ryanair flight from Milan-Bergamo which arrives at 3:10 p.m. you risk missing the last ferry to Paros or Naxos (at 5:30 p.m.) but you could take the last flight to Paros at 6:00 p.m. with Olympic

Note that there is also a flight from Milan-Malpensa with Easy Jet which arrives in Athens at 10:40 a.m., in this case the ferry option is doable without risk and you have 5 possible flights to Paros or 3 flights to Naxos from 1:00 p.m.

There are no flights from Milan to Santorini on this day.

Be careful with European budget airlines. Ryanair, an Irish company, is worse than Volotea for additional cabin or checked baggage, even a glass of water is charged
This is the only low cost company that I have always refused to take, regardless of the attractive price or schedule