was in Santorini last year and loved it, however, I don't think there are enough things to do there for a full two weeks - it's a small island. Perhaps if you were to hop around the different Greek Islands - Crete is great if you like you like outdoor adventure/hiking/mtn biking
Back to Santorini, we stayed at the Heliotopos, and were treated 1st class by the staff and manager. Great two-story room, double balconies, phenomenal view, and the most amazing Greek breakfast that my wife still talks about. I think we paid about ~$110/night. It's also close to several restaurants, walking distance to Fira, and a short bus or taxi to beaches, wineries, or Oia
http://hotel.heliotopos.net/