I understood her 1.5 hours was for Santiago layover. I think she still has 5 hours in ATH. She has another trip --this could become a habit!! haha
I think this is such a brilliant idea. We did something similar in Bangkok. We had hours to "kill" before going to the airport and no hotel (returning from Hua Hin) so we had our driver drop us at a spa and it was divine!! Never boarded a plane so relaxed--we had 4 hours of treatments (a mere $100 for two). The spa even got us a taxi and had our bags in it when we finished--talk about pampering!
Great that the Sofitel is so accommodating. If nothing else, it will give you some comfortable rest when you get into Athens and the hotel. Don't forget, that after a long night flight from the east coast to Athens you will be quite tired and jet lagged. Just sitting in a comfortable pool area might give you the needed rest. Have a great trip.