Keá's most coveted beaches, just a 45-minute speedboat from Athens, is where this cliffside retreat delivers barefoot Aegean simplicity with One&Only's signature polish. Low-slung bungalows (many with private pools) snake down to a private sandy beach; mornings go to kayaking, sailing, and cliff trail climbs. Chef Ettore Botrini leads the kitchen at Ora; Guerlain's first Greek spa is here.

Serifos is the lesser-known Greek island with 72 beaches, a scattering of charming churches, and very few crowds. Nøstos is the hotel to know: 17 bedrooms of natural stone and pale wood among whitewashed walls. No restaurant, but Livadi port is a five-minute stroll. Owners Harry and Bianca share the best hidden beaches and boat trips with the ease of island insiders.

Sifnos is the Cycladic island that serious food lovers have been quietly championing for years, and Verina Astra clings to a steep hillside above it with just a handful of suites. Exceptional views of the island and the Aegean; interiors in whitewashed simplicity. The island's celebrated restaurants, pottery studios, and hiking paths are all easily within reach. A very good and quietly perfect base.