Petra Honeymoon Villas is a beautiful hotel in a spectacular location in Imerovigli. I didn't stay there, but stayed at the hotel right next door to Honeymoon Villas just two weeks ago and got a good look at it every day. The views from Honeymoon Villas are spectacular.
It takes about 15 minutes to walk from Honeymoon Villas to Firostefani, and 15 more minutes to walk from Firostefani into Fira. It takes a little longer to walk back to the hotel because the pathway is uphill all the way (but you could take a taxi from town to a street very close to the hotel to save walking time.)
To get to Oia, which is at the far north end of Santorini, you will need to drive, take a taxi, or take a local bus. Oia is not walking distance from Honeymoon Villas.
I recommend staying in Imerovigli. We stayed there last year for our honeymoon and I enjoyed it a lot better than Firastephani. Oia is just too far from the majority of the sites on the other side of island for my taste. Just make sure you get there for at lest 1 sunset. The experience of all those ppl perched on rooftops and steps is worth it enough. But I still thought the sunset from our hotel balcony in Imerovigli was more impressive with Oia perched in the distance.
I'd definitely go for Imerovigli, a short walk to Firastefani/Fira. Both hotels looked good to us but we didn't go in. We just got back from Greece, highly recommend warm clothes for dining outside at night in Santorini. We had unseasonably high, cold winds and fog at night, hot and beautiful by day.
I prefer Imerovigli to Firastephani for a couple of reasons. Mostly because Firastephani is perched above the town of Fira itself. Fira is very crowded and noisy with lots of traffic at times during the days at peak season. I didn't think the views were as good as in Imerovigli either. There is this serenity in Imerovigli that is just so wonderful. Plus, you are in between Fira and Oia in distance as well. Just my opinion. but I think there are many who share it with me.
I haven't stayed at those hotels but I did stay in Firostefani and found it to be very convenient but away from the crowds. We would take a path that went around the outside of the island with a view of the volcano that took us to plenty of restaurants and shops.
thank you everybody. I'm bying the air ticket tommorow for 21 of august. we decided to go to Imerovigli, villa Anatolli for 17 days (60 euro/night!!!). write to you after