In Nov '06, we went Sun-Wed the week before Thanksgiving and the crowds were light and the lines were short. Most of the Christmas decorations were up but the Christmas parade and fireworks were not running yet.
Last year, we went on Mon-Fri the week after Thanksgiving and saw light crowds and most rides were walk-ons/short lines except for Nemo.
If avoiding crowds is your top priority, I would avoid Veterans Day weekend and the whole Thanksgiving week.