I want to spend some time getting to know Greece with my family of three, and to skip the summer crowds. When is the best time to go? Advantages and disadvantages to winter in Greece? Absolute favorite spot?
A lot of places, especially in the islands, close down around the middle of October. So winter isn't that great of an option. Mid- to late-September is probably about the best time to go. As to a favorite spot, we weren't in that many places, but we really like Naxos.
You can easily travel from mid-April until almost the end of june, with increasing crowds, but still not too bad. Only peak in there is Orthodox Easter, busy, but an experience in it's own. Sept. 1 on is also much less busy, and better if beaches are the plan, and good until like Rick said, mid-October. July and especially August are hot and very crowded. If beaches and islands are not your thing, then winter can be great on the mainland, lots of access to ancient sites, Athens is full of locals, but the weather can be iffy. Many smaller islands basically shut down over winter, but Naxos and Crete can still be active.