I've been to Bandon Dunes the last two Thanksgivings and plan on going back this year. We've had incredible weather and I'm hoping for more of the same.
2008 was sunny, no wind, and 60 degrees for 4 days. 2009 had heavy rain on Thanksgiving day, windy with some sprinkles on Friday, and sunny/warm/light winds on the weekend.
Definitely play all 4 courses. Even in November, it is possible to get in 36 holes a day. You just need one of the first tee times of the day. The courses aren't that tough to walk, though dragging a push-cart through the sand dunes can be a pain.
I'm looking forward to playing Old MacDonald for the first time. Bandon is my favorite with Pacific Dunes a close second. Bandon Trails isn't as strong as those two, but it is still one of the top 25 courses I've played.
If you're driving to the north, Sandpines Golf Links in Florence is a nice course. I've also heard good things about Bandon Crossings, which is a few miles south of the town of Bandon.
-Dave