oooh, bliss! I have been on fabulous holidays to get time all by myself - but not since Ds was born...oh, how I miss it.
I have found the smaller greek places very good - and have always found the option of having a drink with someone I met on a ferry or a walk, or being alone with my book. Paleochora in Crete, Paxos, and a little place on the Pelopponese mainland called Ermione all spring to mind as places that would fit your bill.
Also Tamariu, a little cove resort on the Costa brava way N of the teeming tourist stretch, which has a lovely small beach and lots of friendly cafes and bars, and is on the Camio da ronda (sp?) if you fancy a bit of a coastal walk. And if you really want a quiet spot, a small hamlet called Sa Tuna on a cove with a lovely small hotel with v tasty authentic and v reasonably priced food in their cafe bar. Alos on the Costa Brava, n of Tamariu. I didn't stay there - but while visiting with DP and DS, longed to! Slightly gravelly beach, though.