My wife and I stayed at Miltos' place in the heart of Plaka. The location really could not be more central, yet because we were on the 2nd ant 3rd floors, it was quiet despite the activity on the street. We were there in the beginning of August and Athens was scorching hot the whole time. The apartment had good air conditioning even in 100 F degree heat.
The building is newly constructed within the last 10 years, which is not common in Plaka. Because of this, and because of good upkeep, the apartment is in very good shape with all modern amenities - plumbing, AC, kitchen appliances etc.. clean and working well.
Miltos was a great host, helping us with questions in the lead up to our stay and meeting us when we arrived, tired from a long trip. We had a nice time chatting with him about various restaurants and neighborhoods to explore.
Finally, the private roof deck has a view which defies description. Every night after a late dinner we would come back and unwind on the deck staring nearly straight up at the walls of the Acropolis above us. Fantastic.