Athens stuff that didn't fit in yesterday's already monstrous post ...
Shop for: shoes and jewelery. More shoes than you can possibly imagine, changing with each season. Gorgeous. Start at Syntagma square and walk all the way down to Monastiraki, window shopping. If you are looking to spend some very serious money, head up to Kolonaki.
Order: (tough to narrow down because the food is all excellent)
gigantes (giant white beans cooked with a carrot-tomato sauce - my personal fave)
kolokithokeftedes (zucchini fritters - I have no words to describe them, really)
gyro me pita (the classic meat in a pita. Note that most restaurants don't serve this for a sit down meal because it's street food, easily eaten while walking around - please order the pork or maybe the chicken and avoid the weird processed meat version you'll find in some touristy areas. If you order and the guy pauses with the pita in his hand and asks you something, just nod. He wants to know if you want everything on it. You do.)
katifi (the shredded filo cousin to baklava, insanely delicious when it's done right, available in bakeries, when they feel like making it)
Drink: house wine (rose for summer) in a carafe, cheap. Alpha over Mythos if you're going for beer. Vergina and Keo are other excellent choices but almost never available in the city.
To get around: Walk. And walk and walk and walk. Downtown Athens is not large. Figure out where you are staying and then orient yourself based on the hills. Lykavittos is over to one side and the Acropolis is down at the other. If you get lost, look for a clear view and then aim yourself in roughly the right direction. You'll get there eventually. Take the metro at least once, because it's beautiful. If you must take a cab, make sure the meter is running (the only destination where you need to agree on a flat rate is the airport) and don't get discouraged if you get rejected by a few cabdrivers before you find one willing to take you to your destination.
P.S. I am always happy to talk about Greece. If you have any questions, any time, get in touch and I'll do my best to answer. I'm best with Athens, but I know a bit about most other places as well.