If you can stay longer, there are more spots you can visit:
The peninsula with the three different “fingers” is a real treasure concerning nature and landscape. The easterly “finger” is the monkrepublic Athos , where only male visitors are allowed with special permission. The “holy mountain” Athos rises 2000 m high from the sea. Fortunately from the coastline its possible also for women to see some of the beautiful monasteries.
The middle finger, called Sithonia, is very green and it has a lot of sandbays and very clean water.
There are a few ports you can stay.
Worth visiting is the tiny island “Amouliani” between Athos and Sithonia.
The western part, Kassandra, is quite close to Thessaloniki and therefore very crowded.