Awesome stay at Kalliopi's place! I arrived a bit late, and even though Kalliopi had a flight to catch, she took the time to show me everything in the apartment, ask about my plans, recommend some cool places, and get to know me a little- I wish our schedules had lined up better because she seems like a blast to just hang out with.
Very clean and bright apartment; everything you could need (she even lent me a local cellphone), and about 10 minutes' walk from the Acropolis (if you walk quickly like me!). Kalliopi will give you tons of resources, advice, and probably awesome company. She was/is interested in helping with my trip and cared that I was having a good time in Athens. Definitely recommend!