We also enjoyed O Hamos
Although we didn't eat there, the drinks watching the sunset at Utopia Cafe in Plaka were memorable and as good an experience as anywhere we visited in Santorini. Once the sun sets it's a bit of a mad dash to get a table at one of the nearby tavernas though!
Nice fish/sea food restaurants:
Adamas: Mikros Apoplous
Meat dishes and local receipes: Liofyto, Pepper in Pollonia
Local / Mediterenean cousine:
Adamas: O Xamos, Marianna, Kinigos
Trypiti: Methismeni Politia, Glaronisia, Ergina
Plaka: Arxontoula, Diporto
Palaiochori: Artemis, Pelagos, Sirocco
Ag Sostis (close to Provatas): Tarantela
Restaurants with certified someliers and very interesting wine lists (local and from other Greek wineries):
Armenaki, Enallion, Gialos in Pollonia
Pollonia: Kivotos ton geuseon
Plaka: Arethousa, Palaios
I am so hungry by the end of this post!
So looking forward to our trip and trying these restaurants. Thanks for the info Antonis.