For us, Thanksgiving was wonderful! The kids only miss a few days of school, the weather was perfect, and we really enjoyed all the holiday decorations and parades.
We went in 2005 and are planning on being there this year during that week. We arrived on the Saturday before and enjoyed all the parks. It wasn't that busy at first... but the closer you got to the holiday, the busier it got.
We took someone's advice and avoided the MK on Thanksgiving, opting for MGM instead. While that park was busy, it was manageable and we had a great time! Their parade was awesome and we were able to see Santa come in at the end of the parade! I am so looking forward to that parade this year!

We enjoyed the Osborn lights that evening and finished the night with Fantasmic!
The day after was extremely busy at Epcot, but we had already been there once that week, so we did Soarin' and Mission Space and spent the rest of the day enjoying WS.
My only suggestion would be to make sure that you have ADR's for your sit down meals...it was difficult to get a table on Friday. Not impossible...we were able to eat at Teppanyaki, but that was our only option.
Have a great trip!
