As I do not know the Pegis Hotel I would say, like stanbr, that the Avra Hotel is a much better choice than the Sofitel because:
1/ Avra hotel is at least half the price
2/ The Avra shuttle service is free
3/ If you return the car at the airport you can take the Avra shuttle which will take you to the hotel, you will also take it the next day to return to the airport.
4/ The Rafina port area is much nicer than the airport view you get from the Sofitel (and you could have a last seaview from the room).
5/ By staying in Rafina the evening before your departure you will have a choice of restaurants for dinner that you will not have at the Sofitel
The only advantage of the Sofitel is that you cross the avenue and you are in the airport.
An advantage that you will have paid in the end at least $100 (to walk 50 meters)