If you're looking for a honeymoon spot....stop looking. It doesnt get any better than this. We stayed in the Heaven Suite during the August "busy" season and had the time of our lives. Its incredibly private, peaceful, has drop dead gorgeous views from the highest point in the island, rooms are exquisitely decorated, and the staff treats you like royalty.
- use the staff for reservations/ recommendations. They'll literally reserve the best tables for you at the restaurants of your choice.
- book at least some sort of honeymoon package. We did the basic one with candles, satin sheets, and Santorini wine.
- rent ATV from Jimmy's like everyone else here has mentioned....do the drive to perivoulos (best Sandy black beach on the island we thought) and Perissa. Kamari is soso with a nice boardwalk...but youll need sandals to walk on the beach (very stoney, people burn their feet). Nice outdoor theatre there that's worth checking out though if your looking for a night time activity.
-obviously need to go to Oia to catch a sunset. For us ...we actually went down there "early" one day (7:30 am- nobody wakes up in these islands until like 10:30) and had the entire town/castle to ourselves for pics. Then, came back later that night when it was packed to see the sunset....which really is the best you'll ever see in your life.
-Caldera tour....honestly do some research on this. There's a cheap option where you can take a Viking ship with 100 people...or you can book a semi private catamaran (8 people) like we did which also went to red beach, white beach, and ended at Vlichada. Not that much more expensive really.
- if you have time and are up for it...do the hike from Fira to Oia. Gorgeous.
In summary- we had an amazing time and couldn't recommend this island/hotel any more!