Crete

Perhaps that is a good thing....

While Crete has been overrun with tourists in the last decade ( especially the western side)...there are still parts ( especially on the eastern side) that are wonderfully authentic and almost undiscovered.

Crete is a large island with lots of infrastructure, a few old Venetian era walled cities, mountain hiking and good beaches. It is popular but can absorb a lot of visitors without being overly crowded.

Here are some images

https://www.flickr.com/photos/stanbr54/albums/72177720318394812/ small tour company from Chania Crete. They have tours that cover west Crete quite well.
https://www.flickr.com/photos/stanbr54/albums/72177720318408008/ Images of Cretes lovliest city with Venetian era old town.

David, Rick is a lovely person, and his book gives valuable guidance for Athens and for inland destinations -- however, remember, his tours do not cover the islands ... and his book relfects that. He usually just mentions Hydra, for trip-goers or tour-takers who want to say, I've been to an island. Try to go beyond the the RS walls, and do some homework in some comprehensive Greece Guide books. Your library is full of them. And BTW, older editions are better.... fewer color photos, but fuller text & history, to tell in-depth about ruins, history, nature, culture .,.. and the reasons WHY to visit an island like Crete.. For the latest on transport, hotels, restaurants and color pix etc, the internet is great -- but you won't learn the Why

Janet #3 that’s so true and such valuable advice! I remember devouring my parents’ travel guides on Crete and Greece when I was young. Some black and white pictures, maybe one or two in color if you were lucky, but mainly text with a treasure trove of information about history, people, food, places of interest. That’s how I learned about Crete’s fascinating history at a young age and it still helps me to put places, events and customs in perspective when I’m there.

As Janet suggests, look for travel guides in bookstores and libraries. Just keep in mind that Crete is almost like its own country and often gets its own travel guides, sometimes several hundred pages long ( at least with European publishers). This is also why you won’t typically find Crete in guides about the Greek islands.

Rick Steves book only features 2 or 3 islands that cover hardly 2% of the Greek islands worth exploring.
It's a selection; it shouldn't be interpreted as a comprehensive travel guide.