Greece in July for 8 days

I have read that both Santorini and Mykonos are heavily over-visited.
Have you considered a cruise? For example: https://au.ponant.com/the-mediterranean-at-the-heart-of-the-greek-islands-au110724-10

I definitely don’t want to do a cruise due to seasickness but ferry/ boat rides are fine.

If you don't want to take a cruise because of seasickness, I strongly advise against taking the ferry. It will be much worse than a cruise ship,
If you want do take a daytrip to Mykonos you will have to take a fast ferry from Seajets, and these are the worst for those who get seasick.

It's up to you...

Check ferry timetables on ferryhopper

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

(select a Santorini-Mykonos, the date, and validate an "Add Return" on the same day)

Know that Mykonos is one of the most expensive places in Europe, a destination for the thousands of cruise passengers who disembark there every day, and above all a party island where showbizz stars like to show up. When you know some other Greek islands Mykonos is closer to the Las Vegas theme hotel than to the traditional Greek islands atmosphere.

With eight days, don't discount the mainland--there is so much to see that does not require waiting around for flights or ferries.

We flew from Athens to Santorini instead of taking the ferry. We enjoyed our 3 nights in Santorini. There is a lovely coastal walk which is downhill from Imerovigli to Fira and has spectacular views. We took the bus to Akrotiri which is an amazing archeological site. The promenade in Oia early in the day and the blue domed churches and windmills there are very picturesque. The sunset from Oia Gefsis restaurant's upper terrace was beautiful! Then we flew to Athens for a few days before we flew home. There are other places to research on the mainland as well.

Thanks for the helpful tips, I will definitely fly to Santorini and hope to spend 3nights there. I do want to visit another island with good beaches before going to Athens. I heard that beaches at Santorini are rocky. I would appreciate any other recommendations.

I have a similar plan for September..
Santorini and Mykonos are too far from Athens..and overcrowded.
Anybody from this forum, recommend more accessible islands that is just as beautiful w/o the crowds??
thanks..

When it comes to taking a day trip to another island it is best to contact a local travel agency.
Most ferry schedules are not made for this type of trip, they are mainly means of public transport which are used to transport islanders and goods and not for day trips to see a other island.

And what's the point of going to an island for just a few hours?
It's like visiting a big city and staying on one street.

As for the beaches
in Santorini, there are some (black) sand/pebble ones to the east of the island in Kamari, Perissa or Monolithos.
The same kind of basic beach that you could find in all the countries around the Mediterranean Sea

I am interested in other islands closer to the mainland with similar scenic views and beaches to Santorini please. Thanks so much.

If you're keen on experiencing beaches, Milos Island or Ios Island could be your best bet. These islands are just 2 hours and 1 hour away from Santorini. Milos is famous worldwide for its amazing beaches and Ios, known for its clean white sands, is often visited by the younger crowd. Just a heads up, if you're prone to seasickness, remember that ferry travel is common in Greece.

But if you're not too thrilled about multiple ferry rides, Athens - fly to Crete, catch a quick 1.5-hour ferry to Santorini, and then fly back to Athens might be the best option for you. Crete, a big island, is filled with beautiful beaches and offers great places to stay such as Agia Pelagia, Elounda, Chania, or Elafonisos.

For a close-to-Athens experience, I recommend Agkistri & Hydra islands.

Thank you MeridianMary for some wonderful options. I usually don’t have a problem with ferry rides of 1-2hrs. I just can’t do multiple day cruises where I have to sleep on board a ship.
I might rethink Greece and opt for Switzerland or Austria instead because we only have 8 days this time. Also maybe visit Greece in September another year for 2 weeks. I am daunted by the crowds, having to book ferries, flights.

Yes that is why I suggested the mainland. I had 11 days and did not want to deal with ferries, and there is just as much coastline on the mainland.
Where are you flying from? Sometimes you can get one-stop flights to certain islands, like Crete.

I’m flying from SFO and my husband from Munich/ Frankfurt.

I believe Lufthansa flies to both Heraklion and Chania.