One of my daily reads, appropriately titled Daily Frappe posted an item about an article in the NY Times about how Thessaloniki (or "Salonica") has suddenly become more popular, one reason being that out of its population of 1 million, 95 thousand are students. That's like Kyoto - about 1/10th of the population (also a million) are students, so there is a youthful vibe here as well.
I have been to Thessaloniki twice - once when I was 10, and the other time 17. Obviously when I was older, so was my cousin and she took my sister and I to the cafes, the bouzoukia, etc. etc. Personally, I like Thessaloniki WAY better than Athens. First, because it is (or well, was) a place that not the usual tourist would go to - it is a bit of a trek out of the way to get there. Second, I even got the feeling that it was kicking back in 2002. Third, the view! My cousin lives in Panorama (the "Beverly Hills of Thess/niki) and she has a view of the bay which is mainly centered on Aristotelous Square. The square has a unique shape, as it is not a square, and was the focus of a particular ad from 2006: The awesome thing is that nothing was done to enhance the photo; Aristotelous Square is shaped exactly like that.