I enjoyed Athens as a city very much. There is a lot of history to take in and photo opportunities to be had. There are various bars and many places to eat. I would certainly come back. The only negative thing I have to say about this great city is that in my experience, the taxi drivers are generally useless (not all).
Insider Tip:Unlike other major cities, Athens taxi drivers don't always know where they are going unless it's a major tourist hotspot. Be prepared for that.