3 Weeks in Greece

Of course, but whether it is of interest to you is a different matter. I had a trip planned for the north that was cancelled by the pandemic (still plan to do it one day). I was interested in the Pelion peninsula, Vergina, and Thessaloniki, plus Meteora which you already have on your list. I have found the Bradt Guides the best for both mainland Greece and the Peloponnese.

Happy to see you are taking the opportunity to visit Greece.
In my opinion there is way more to do and see in Crete then Rhodes. Crete takes a month to see and experience most of it. Its best to choose one section of it and explore fully as you plan to do.
You can make Chania your base and explore the west side from there. You might consider the excursion boat to Balos lagoon. You get a shipwreck, two lovely beaches and a pirate fortress on the excursion. The boat departs from Kissamos about a 45 minute drive from Chania,

When we leave Chania we normally go south to Paleochora or Sougia. Paleochora is larger but Sougia is a lovely small village highlighted with mountains the sea and some sea caves along with three of the best tavernas anywhere. Its quite laid back and the bonus is you can take the coastal ferry to Agia Roumeli where you can do the famous Samaria gorge hike from the bottom which is the flattest portion of the hike.

If you want to stay there you might want to look for a hotel sooner than later.

Delphi and Meteora are great sites and you will not be disappointed. They are a 5 hour drive apart.
You might want to consider Delphi and Nafplio. They are closer together. Nafplio is a lovely seaside city. Be sure to find a hotel in the old town.

There are several important ancient sites within a short drive of Nafplio.

Thanks so much for the suggestions, they are very helpful.