The areas which are relatively close to the location of the school are Kaisariani, Zografou, Ilisia and Pagrati. You can find a place to stay via https://www.airbnb.gr or https://www.booking.com
The area around the 'Andreas Syngros Hospital', in particular, is very close to the venue, with lots of nice small hotels - it is also very close to the city centre with several museums, coffee shops and bars nearby (it is also relatively close to 'Megaro Mousikis' subway station, which has a direct connection to the airport).
If you wish to stay somewhere close to the city centre, we suggest the area around Syntagma, Kolonaki and Exarchia, with relatively easy transportation to the area of the school.
Hotels
TBA