Large family travel

A few questions to better understand your request.

For accommodation, since you say "that won't break the bank" what is your maximum budget per night?

What time of year?

I guess there will be about 10 people, how do you plan to travel from Athens?

The possibilities for traveling on the mainland with public transport in Greece are rather limited.
Can you rent at least two vehicles to transport everyone, or would you prefer an organized transfer?

Have you considered the possibility of going to an island?

Finding Airbnb type accommodation in Athens should be possible, possibly several appartments or studios next to each other in the same building.

This may be more difficult although not impossible by the sea on the mainland.

On the islands, there are quite a few possibilities to find a 4 or 5 bedroom villa provided you book well in advance, stay at least 5 nights and can afford it. Allow at least €500 per night in low season (May - early June - October).

At first, I thought we would stay in a villa/house on an island and travel to Athens to see everything it is famous for. I read on another forum that it is not always feasible (timewise) to take a boat back to Athens. How hard would it be to get back to Athens from an island? Breaking the bank trying to say $1000 or less a night.

Heartland, since you have 9-10 months before your projected trip, you have time to do some homework on your own -- otherwise you are asking us to organize too much information, and make too many decisions for you -- in essence asking us to be a travel agency. To get all problems solved for a large group without requiring any research, it may be good to consider using an agency -- that's what they're good at. And they don't cost the earth and can avoid costly mistakes.

There are 2 Athens-based agencies that have excellent rep & reviews for dealing online with N. American clilents: Fantasy Travel and Dolphin-Hellas. They know the options much better than a US agency... and if there's a sudden glitch during one's trip, they're right on the spot - you phone, & they fix. They don't plunk you into a tour -- they do an individual trip plan for your group. Here's the deal -- you email them with All Relevant Facts • Approx length of trip (NOT counting travel to/from) • Approx desired timing (ie. May 20 - June 5) • Number of Adults / Number of Children (WITH ages) • Approx number of bedrooms needed AND type (i.e. double bed/ 2 twin / double w. crib etc). * Budget range per night for full accommodation • Mainland transport /preference --i.e. large bus w. paid driver or (number) rental cars ( full-size vehicle = 5 people max) . Once you give these key facts, you can then give your "wish list" of destinations (when you've done a bit of homework to identify your favorites). Email both at once, and see which answers most quickly, and compare their offerings.

NOTE: since your post hints at only 10 days actually IN Greece, you may not be able to visit "famous islands" because the cost of flights to/from could be major... and ferries to these island could take up 5 - 8 hours... too much for a 10-day Greece visit. However, if you have time to research, you may find the perfect solution is a destination in the Peloponnese Peninsula, near NAFPLIO ... wonderful beaches, fascinating ancient sites, great walks and views... and only 2.5 hours from Athens on modern intercity highway. This is a wonderful Non-commercial website http://www.visitnafplio.com/ that gives full info & wonderful pix about the town & surrounding beaches, AND all the lthings to see-do -- click every link!
NOTE #2: Having a villa sounds wonderful but it many islands, these are not located conveniently,but instead are inland. Then people may have to constantly get in rental car(s) just to reach the beach, or find cafes and tavernas for meals. You may avoid constant driving with better locations -- right on sands and near to shops, restalurants and historic sites -- if you can book 4 units in one hotel, with a terrace for gatherings. By thinking so far ahead, you have a good change of booking such.

As for Athens, you probably can do best by setting up your own family tour -- with that many it can be quite cost-effective. The Athens-Walks Company (best reviews) has standard tours, but also designs individual tours for groups like yours, suited to your timetable & needs. When looking for Athens accommodations, these days booking dot com does a great job for famiilies, because it now has private apts for rent as well as hotel rooms. Often these are better located than hotels w similar rates. In addition, this agency may have more safeguards and cancellation/date change provisions than VRBO or Airbnb. Keep in mind, unless you have the budget of a sultan, you're not going to find an apt for 10 in Central Athens.

Perfect!

That is what I needed to hear! Thank you, Janet! I am used to making all of our travel plans on my own but as our family has grown from two siblings and their kids to 2 sets of parents with adult kids & their spouses, and a few teens it has become increasingly difficult. This is why I wanted to start asking about this trip now instead of later but I didn't know what to ask....

Thanks for the guidance! I appreciate it!

Sorry, I didn't see that it was for May-June. But you write 2026, is that for the year 2026 and not 2025?

I agree with Janet that it would be better to contact a local Greek agency.

If you want to go to the islands I will also add Aegean Thesaurus Travel which is a very good agency existing since the 80s and based in Sifnos

https://www.thesaurus.gr/

Organizing such a trip requires a lot of time and research.
I did it twice, once for 6 and another for 8 people, and although I was part of the trip, that I know Greece, its islands and most of the mistakes to avoid, it was weeks of work.

If you are ready to do that, why not.

On the other hand, I do not agree with Janet's NOTE#2 regarding the villas on the islands (sorry Janet).

There is quite a choice of villas near the sea and a beautiful beach, sometimes even with a swimming pool. And also within walking distance of restaurants, bars or services.
Staying in a villa has never been a problem for me from this point of view.

Regarding cars it is recommended to have 2 cars when you are 8 or 10 people. Not necessarily to go to a restaurant or go shopping, but to visit the island. It's 90% of the convenience of a rental car when I'm on an island.

But I admit that I am special because, for example, I cannot understand why people cross the Atlantic, fly for hours to spend their days in an air-conditioned villa by a swimming pool or in a sunbed beach. You might as well find this kind of “adventure” near where you live.

For your information, here is where I took my uninitiated travelers to Greece on the island of Paros the second time

https://villavanta.com/

It was late May, before Covid. Less than €600/night. Right next door there are restaurants, bars, a minimarket, a huge sandy beach, and even a bus stop

I can't offer specific companies, but have you considered 2 side by side apartments through a short-let agency?
AirBnB allows you to click a host and see what else they are offering. Sometimes the host is a company (often their logo is the avatar). You may also want to see if you can find the company online but off AirBnB and ask what they may have available to suit your needs.
It is a little difficult to fully know your intention of staying on an island but don't consider it if you were looking at it as a homemade for daily trips to Athens sites.