Athens will be great for a couple of days, but I would highly recommend some day trips to take you out of the city as well (you can do a day trip to the island of Aegina, it's only an hour away by boat. Also you can get down to Glyfada on the coast with public transportation. Third short trip would be to Sunio and the Temple of Posidon - all three should be very easy to arrange and you can be back in Athens by nightfall).

With the new government, the number and intensity of the demonstrations seems to have died down a bit. I would keep an eye out and just avoid the areas of any demonstrations. Also pay attention as strikes have the potential to disrupt travel (I remember my first trip, I had to wait for four hours for my plane to take off due to an air traffic controllers strike). It's a great country with amazing food and great people. I am heading back in a couple of weeks.