I went last January and saw just about all the major sites. I have to run out right now, but I will come back and edit for recommendations when I get back. :)

Have you been to Rome already? If not, holy crap go there! 1 day in Athens is enough to see and enjoy the sights. After that you will be disenchanted by the smog, stray dogs and meth heads riddling the streets. If you go to Greece, see Athens for a day or two and then get out to an island. The city is not charming. At all.

I fell in love with Rome, The Museum of Modern Art there is incredible. Vienna is also a lovely, friendly city with great art.

Just back from a fortnight in Athens which was great. Here are some reasonably priced but clean and central hotel possibilities

http://www.hotelphaedra.com/

http://www.tempihotel.gr/index.html

http://www.attaloshotel.com/

The major sites - the Keramicos, Roman Agora, Acropolis, Theatre of Dionysus are now all linked by a pedestrian area and so it is easy to stroll about. They are also free on Sundays at this time of the year.

The Byzantine Museum has recently been completely renovated and is well worth a visit. They currently also have a (small) exhibit of Andy Warhol paintings, if that's your thing.

The new Acropolis Museum is also wonderful.

Ekathimerini, a Greek newspaper, publishes a weekly English language paper - Athens Extra - which lists temporary exhibitions, museum opening hours and, at the back, a useful map. You can download a copy here

http://www.ekathimerini.com/

Have a great trip.

Alan

Forgot to answer your question about vegetarian meals. There's one vegetarian restaurant in Plaka, the tourist area of Athens below the Acropolis. It's called the Eden and is on Lissiou, a small side street between the Acropolis and Adrianou, the main pedestrian road through Plaka. It tends to do vegetarian versions of greek dishes eg moussaka with soy mince. I've taken vegetarian friends there at various times and some liked it and others didn't.

I prefer, if I don't want to eat meat, to just get something in a normal restaurant. Most places have a range of salads, including the ubiquitous greek salad with a slab of feta. In addition look out for gigantes (large beans in a tomato source), horta (stewed greens) and briam (mixed vegetable stew.)

A favourite restaurant of ours is the Byzantino, on Kydathinon at the Hadrian's Arch end of Plaka. They generally have one of the above as a daily special. Their food is well prepared, reasonably priced and they have a good location in a pedestrianised square with space heating which makes it possible to sit out even during the winter.

At the other end of Plaka you might like, especially for lunch, the Dia Tafta. This is on Adrianou almost opposite the back of the Stoa in the Roman Agora. They do a (very large)boiled vegetable plate, and a similarly large mixed salad plate. Ingredients of both depend upon season.

Hope that helps.

Alan