I must agree with KLouis.....but even more on the conservative side. The experienced tourist who frequent Greece have a rule never to travel from the islands the same day as an international flight. Weather, winds, strikes, late incoming flights, etc can cause chaos....and there are many stories of people missing their flights, especially when the connection in Athens is on a different airline.

It's not Athens that is the problem .... its making sure you can get off the island to get to Athens.