We had a wonderful stay at Stratis' place. The location is just about perfect - walking distance to everything and less than a block to Monastiraki Square - but just off of the main road and reasonably quiet on the 6th floor (and has an elevator)! The apartment itself was very clean, furnished nicely and extremely comfortable with plenty of space. The balcony with Acropolis views was also wonderful.
We'd definitely stay there again if we ever return to Athens!