We have gone to Disney the last 2 years for Thanksgiving (2004 and 2005). You will love it! The weather is fantastic, and up until Wednesday before Turkey Day, the parks are not crowded.
We ate at Whispering Canyon in 2004 and at the Trail's End restaurant in 2005. We loved them both, they both offered traditional Thanksgiving foods (turkey, dressing, etc.). Whispering Canyon is served family style in a skillet on your table, when you want more they bring more. The wait staff at WC is AWESOME! They had a wooden horse race around the restaurant for the kids, and then a sing-along for the dads/uncles/grandpas. It was a lot of fun and very entertaining. If you choose WC, make sure you have someone in your party ask for a large water and ketchup. The result is HILARIOUS!!
Trail's End is buffet style. There isn't any entertainment, but the food was good. We chose to eat early and then head over to the campground for the Campfire Sing-Along and Movie with Chip 'n Dale. You could also choose to watch the electrical water pageant on the lake.
Have a great time!!
The Petti in GA