All the travel forums tell the same tale. And I have seen it in person. Every site in the Med that is within 1 hour of a cruise ship port, is inundated from 10am until around 4pm. As an independent traveler, you just have to work around this or dive into the fray. Just follow the umbrella . . .
Por: Santorini I have covered. I blew our usual budget & bought this view for 4 days:
Ian