Long story short, if either of the units at the Hector Cave House are available during your time in Santorini, book them immediately.
Everything about this place was perfect; from the welcome wine/snacks, to the service and attention to detail from Giannis, Dana, and Dmitris, and especially the view and location! It is right near the most famous of the blue domes and prime sunset viewing spots being up the stairs from the main walkway provides plenty of privacy and seclusion from the crowds. The interior was well appointed and really comfortable - the three couches are seriously more comfortable for sleeping than our normal bed at home and the king bed up on the elevated platform in the back room is like a super comfortable bunk bed for adults.
We wouldn't even consider staying anywhere else whenever we return to Santorini!