As everyone would expect there is MacDonald's at Eleftherios Venizelos (Athens) Airport.
The food/drink at the airport is more expensive to do the same in town. Even Grigoris charges more at the Airport. However, philo-laikos MacDonald's sells the food at (almost) the same price in town. (I wrote 'almost' just because I did not compared the price lists, but my impression is that the price is exactly the same).
On the day I was leaving for Japan, we stopped at MacCafe for a coffee and we were offered beautifully decorated cappuccino.
If I remember well, we paid only 1 Euro a cup, because there was a promotion going-on.
Too much chocolate changed the taste of cappuccino, but nonetheless we loved the artfulness of the barista. :)