We had a very comfortable stay at Sofi's place. It had everything that you need, and Sofi was a great host. Kitchen was pretty good equiped (microwave etc.) although it was a bit small, and the table was quite rickety. It was nice to have a smart tv with netflix in the bedroom. If you are tall (1.80+) mind you head in the shower. Outside area is really nice if you visit in the summer.
Very good location - safe, close to the center (walkable), easy access to public transport (bus), Lycabettus Hill is close and you should definitely hike up to there.
Recommend to go to the following store for grocery shopping: Sklavenitis at Leof. Alexandras 106. They have fresh bakery and is bigger than the normal supermarkets all around.
Side note: For public transport be aware that busses dont always go. We found 230 to be quite reliable.