Don't overdo Athens
Of course there's the archaeological sites and the museums, which are worth your visit, but the city itself is not worth staying for. Every street is so dirty and people in tourist business are often morally problematic. Taxi drivers lie in our face to cheat our money. Girls selling flowers in the street cheat you for money. Don't trust anyone. Watch out for theft! And when you're done with museums, go to the islands instead. They are much cheaper and prettier. You'd be surprised after Athens.