We stayed in Avaton for 5 nights in May 2012.
I have to say this is a very impressive hotel and the thing that makes it that way is (among all other things that are great) - the service. Laura and Marcus (as well as other staff members) make sure none of your wishes is left unfulfilled.
The hotel itself is build on one of the highest parts of caldera with stunning view and BEST sunset view (really, once you will see the "famous" Oia sunset and compare it to the view you have from your balcony or even bed in Avaton, you'll see what I am talking about). It is very stylish, design oriented, boutique hotel. It has 9 rooms and suites. Guest were couples in 30-40ies, quite, all enjoying and relaxing.
The breakfast is excellent, everything we tried was great and delicious. You let them know your wishes and time of delivery day before, and the next morning the breakfast is served in your room or balcony so you can enjoy the view and good food. Also room service food was excellent.
Rooms are very nice, Santorini (cave) style, but modern, with attention to detail. We were upgraded to a deluxe room, which is on 1st floor with balcony. Each room is equipped with a wi-fi router, so the reception is excellent (although I had some problems with internet, but I believe it was the external connection). Also, the TV in room has DVD player so you can bring your own DVD's for case of bad weather...
There is a SPA in the cave, which is turned into a restaurant in the evening. Have tried small IR sauna which was OK, but turkish sauna (stam-room) is little bigger and I guess also better. Haven't tried the massages.
The location of hotel is at the end of Imerovigli village (public/free parking is 50m from hotel). Imerovigli itself is a quite village, with some tavernas and nice hotels. We liked it that way that is why we have chosen this place, but if you want action, Thira would be a better choice.
I would definitely go back to this hotel. There is only one thing that was bothering us, that was the wind, which was blowing (as the location of hotel is very open on all sides), but I guess this could be a bonus if you are there in hot summer months. Highly Recommend it.
Thank you all we had an excellent time!
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC