While Spetses seems more geared to day trippers and wealthy Athenians with island homes than it does to overnight guests, this 19th-century sea captain’s mansion is the exception. The shady garden is enlivened with sea-motif mosaics and a pool, while in the cozy and elegant sea-view guest rooms, handsome tile floors are covered with old carpets and big iron bedsteads are dressed with fine linens.