I recommend Drosoula and her place for the most convenient stay in Athens. We arrived late, after 10:30 pm but Drosoula was there waiting for us. Her English is very good, her home has everything that you need, we even had something to eat and drink in the fridge.
Right in the middle of Athens, you are close to everything, only walking distance. If you are not very fancy when it comes to eating, follow or ask for the recommendation on Veikou street no 39, good food and cheap. You will save plenty of money.