I have been in Athens for one night only by staying at Christina's place as I had to catch my flight the morning after. It's very close to Syntagma square. Here you can find numerous cafes and restaurants, and most importantly the bus stop, where X95 bus takes you directly to the airport for 5.5 euro only in about one hour time. Place has AC and is clean and quiet. As pro and cons, there isn't a view as the window opens in the internals of the building but that gives you on the other hand one of the quietest nights you've probably ever had in your life. I highly recommend Christina's place. She has been very helpful and responsive giving me all the details needed to reach the apartment. Thank you Christina! ciao!