Paros and Sifnos

From May 28 to June 3 that's 6 nights, and that's actually only 5 really useful days. I will recommend you to choose only one island Paros or Sifnos. There are enough things to do and see on each of these two islands to stay there for 5 days.

Seeing 2 islands in 6 nights will only give you 2 useful days on each island. Even if you don't want to see everything, it's very short

In case you still want to go to these 2 islands, Paros having an airport (but not Sifnos), do you plan to take a flight to or from Paros or rather to do everything by ferry?
Still if you want to see these 2 islands there are basically 3 possibilities:

1- Do everything by ferry

2 -Go to Sifnos by ferry then Sifnos-Paros by ferry, then Paros-Athens by plane

3- Go to Paros by plane, then Paros-Sifnos by ferry then Sifnos-Athens by ferry

Be aware that if you prefer a moderate budget, between Paros and Sifnos and between Piraeus and Sifnos there is no traditional ferry every day. Daily ferries are high speed Seajets which are about twice as expensive

I'm trying to stay away from any ferries that are several hours long - sea sickness concerns, so I would be flying from Paros back to Athens, as I assume the ferry from Sifnos to Athens would be several hours.

I'm driving from Nafphlio to Athens May 28, to catch a flight to Paros in mid to late afternoon, then I was thinking I might take a ferry on to Sifnos that same day, if there is one. That would give me May 28, 29, and 30 in Sifnos. Then I would take the ferry from Sifnos back to Paros on 5/31, and have 5/31-6/2 in Paros before flying back to Athens on 6/3 for a return flight home on 6/4.

My wife and I like to see a few sites, but mainly like to take in the local culture, go to a couple of nice beaches, shopping, eat wonderful food. If I choose only one island, which one of these two would you choose, or is there another island we should visit, instead.

Thank you so much for your help.

I was thinking I might take a ferry on to Sifnos that same day, if
there is one

Unless you can be at the port of Piraeus on Sunday May 28 before 8am, you will not be able to find a ferry to Sifnos

Otherwise the Blue Star Naxos departs to Paros daily around 5:00 p.m. and arrives around 10:30 p.m.
(and of course, as for Sifnos, there are others earlier in the morning)

If none of these options is possible for you, you still have the option of taking an Athens-Paros flight on May 28.

I know Sifnos and Paros quite well (I've been going there for over 30 years) and I'm sorry to advise you to take one of them off, but honestly if you "like to see a few sites, but mainly like to take in the local culture, go to a couple of nice beaches, shopping, eat wonderful food" the 5 days you will have will be perfect for a single island.

Going for example to Sifnos on 28/29/30 as you plan, means that you will arrive on the 28th in the afternoon, will have only the 29th to do everything you are talking about (beaches, restaurants, sites, walks, culture, landscapes), and will already have to leave the next morning.

Furthermore you have chosen two islands which are not on the same ferry routes, and although they are geographically close, getting from one to the other is less easy than you might think.

So, from an access and logistics point of view, the best option is to choose Paros.

Up to you.

If you want more info about Paros (or Sifnos), don't hesitate

Now I'm going to mope because I eliminated Sifnos which is one of my favorite islands :))

Addendum:

I forgot to add that from Paros you can go to Antiparos (15 minutes by boat from the port of Punda) and if you want, spend a night there.

https://antiparos.com/

https://www.paros.gr/en/