Santorini is on my list! I've heard a lot of positive words about the island :)
I was in Greece 6 times, 2 times on Rhodes, Crete, Kos, Zakynthos and a week ago on Corfu. I definitely recommend you this last island. On my profile soon there will be an extensive entry in English, for now it is in Polish. :) I love Greece and this atmosphere!
RE: Is it WORTH to visit ZAKYNTHOS?