I found where everyone was: the kitsch tourist shop district around Monastiraki, which is right by the Agora and under the Acropolis (which I still haven't seen...waiting for my wife).
I walked around Monastiraki, avoiding entering the kitsch shops..."No, I don't want that alabaster statue, Greek flag beach towel, or spartan helmet, even if it is 50% off..." What impressed me about Monastiraki is the abundance of graffiti. Now, I must first say that Athens is full of graffiti, even in the nicer areas. The amount of it makes it seem like it is officially or tacitly tolerated. That being said, in Monastiraki, the buildings are covered. It almost makes me wonder if someone (besides the artists) want it to be there. This isn't a "scary neighborhood;" it was full of tourists buying souvenirs in the shops that were open amongst these closed shops (I just avoided them in the photos). Every store in Athens has a metal garage-type door that locks at night or when the shop is closed. Since I haven't been here on an ordinary day, I don't know, but I'm guessing that these are usually open, but the shopkeepers are just celebrating the holiday. Enjoy.