Meteora is the one place in Greece where the setting beats the sights. Sandstone pillars, up to about 400 meters tall, stand above the plain of Thessaly, and from the 14th century monks built 24 monasteries on their tops, hauling people and stones up with ladders, ropes and nets. Six are still open to visitors, and they've been a UNESCO World Heritage Site since 1988. The name means "lofty".
Three days is the right length, and November is a good month to do it, if you plan around the rules. Each monastery closes one day a week, in winter sometimes more, and the days are staggered. They also shut early, between 2 and 5 pm, and the sun sets around 5:20 pm in mid-November. The six monasteries are only a couple of hours each, but the closing days, the steps and the short light make two days the minimum and three comfortable. The third day goes to Trikala, because it's the day you'll want a break from climbing.
The plan starts on a Saturday, because in winter all six monasteries are open on Saturday and Sunday. Day one is the big three along the main road, day two is Holy Trinity, Saint Stephen, Anapafsas and the hermit caves, and day three is Trikala, while Saint Stephen is closed anyway. Base yourself in Kalambaka or Kastraki, and read the closing-day tip before you change anything. If Meteora is part of a longer Greek trip, the Greece country page has the rest, and 5 Days in Athens and 5 Days in Thessaloniki cover the two cities most people arrive from.