Yup I think I have the same picture from Nikoletta's veranda overlooking Apollonia and the seaside. I too was won over by Vathy and eating with my table and feet in the sand! Beautiful. As for Serifos we did go for 3 days in the end (although I left Sifnos kicking and screaming) and enjoyed it. Its good to see the differences between the islands. We rented a car for one day on Serifos as the transportation wasn't as efficient as Sifnos which was great we hit all the beautiful beaches and had a wonderful lunch in Megaldo Livadi (again tables in sand in a quaint bay). Coralli was fully booked when we got there, but we lucked out as we sat on the Livadkia beach contemplating what to do a nice Canadian man overheard us talking and next thing we know we have a beautiful apartment above the flower shop in town to stay at for 3 nights. So good vibes from Serifos as well.