concerning to the ''Medusa'' hotel, it is close to the center of Loutsa, but there is much noise around the area and you will surely need a car to go to the spot of Loutsa. The best choice for you might be the Sofitel, just close to the airport...you will earn a few minutes of sleep in the morning!!!!!!!!
About the kite, as the guys told you before, the most usual number for Loutsa is 9, for 20-30knots. Of course, it is a good chance for you to see also the other kitespots and the monumetal Athens as well, such as Akropolis, Parthenon etc. So it would be great if you could stay a few days more!!!!!
We are pleased to help you with anything you need, while from this summer we start our new project ''KiteInAthens.gr'' which includes daily excursions to the closest kitespots in Athens.
Take a look to Jeremie's video at http://kiteinathens.gr
to see some of them. A few more kitespots are Drepano, Nafpaktos and Nafplio.