We are taking a cruise out of Athens in November and wonder how much time we should spend in Athens or should we drive out to the countryside.
I think Athens deserves at least two nights, either at the beginning or end of the trip. The Acropolis, Agora, Museum, and the Plaka are world class sights not to be missed. If you have more time, Delphi (one night two days), the Meteora(two nights,plus 1/2 day travel each way), and Nafplio (two nights) are all good options depending on your interests.
I would give Athens 2 days and thats it. Rick recommends the same. He has a great walking tour of Athens on his site here that will get you to see everything in 1 day and then focus on the big sites like the Acropolis on the 2nd day.
Of course you might finish the tour fairly quickly if certain piles of rubble don't get you excited. Then the whole thing would only take 1 day.
But take your time and research what you want to see. But 2 days in Athens and you will want to get out. Not much after that other than the usual big euro city atmosphere of shopping, fashion, and flea markets.
I recommend be in Athens for two whole days. In November I do not recommend traveling to the north of Athens (Delphi) because it could have snow on the paths, making it hazardous. Athens can have cold air and rain in November, but you can be in museums in Athens. The National Archaeological Museum, and the Benaki museum are great !. And, remember the museum that is on top of the Acropolis.
Read about the recommended places for overnight accomodations in Athens, in the book "Lonely Planet: Greece".