Three countries on a rental car. If you are not a big fan of lying on the beach for more than two minutes, organized excursions annoy you, then traveling around Europe by car is the thing.
I have been to Turkey 23 times and lived in hotels from 5*+ to 1*. Not many people risk going to Turkey to a hotel below 3 *, but they have their own rather significant advantages.
Quite by accident, I was brought to the Greek island of Zakynthos, and according to impressions, it overshadows the usual beach places such as Turkey, continental Greece, Spain, etc.