We had a pleasant stay in the AirBnB of Giorgios and Konstantina. They were accessible all the time and made us a very warm welcome. Konstantina also had many tips for us.
The AirBnB is in a very quiet quarter ca. 25mins by feet or 10mins by bus from the centre. There are nice smaller bars just 5mins away and also the Panathinaiko-Stadium is just 10mins. The Apartment is worth its price and has AC which is very helpful in this hot climate.