Never been there during Thanksgiving but you probably want to take any info you've heard with a grain of salt. The new MYW passes, which are only about 3 weeks old, not include DisneyQuest admission as a Plus feature. In the past, the only way into DQ was to either have a Premium Annual Pass, Ultimate Park Hopper or buy single-day ticket to DQ for about $30. Now that it's a Plus, I bet crowds are going to increase dramatically.
In general, watch out for weekends and afternoons (locals on their APs), and any day with poor weather that would drive people indoors.