SPA
I must recommend getting at least one massage and a facial while you're there! Elpida Manousogiannaki is the go-to massage therapist on the island and for good reason. She is AMAZING and so are her colleagues. They come to you, bringing their massage tables and super soft, clean linens. I highly, highly, highly recommend the traditional Greek olive oil massage. Here is a link to her website which has all her contact info: http://www.santorinimassage.com. And, no, nobody paid me to say this. I paid full price for my massages and I would happily do so again! They were pure bliss.