The entire week of Thanksgiving will be crazy. If you are willing to take them out of school, I would seriously consider going the week before. There will be a huge difference in the crowd level.
You will find that the issue of whether to take kids out of school is pretty much split down the middle, with both sides feeling very strongly about their opinion. It is a choice you have to make based off of many things....your personal feelings, the school's policy, your child's grade level, whether they are struggling in a particular subject, etc.
Do what feels right for you. We take our kids out of school for Disney trips for the time being, but if we ever felt like it would have a negative impact we would stop. Also, I used to be a teacher and I had no problems with my students missing school for a trip.
Just do what ever YOU feel comfortable doing, regardless of others opinions!
(I should also add that my son missed a week of school in December for our WDW trip, and not only did he have no problem catching up on the work he missed, he continues to be at the top of his class in all subject areas)