The days before Thanksgiving are the busiest of the week. There are few AP blockouts those days, and the locals flood the parks. With Cars Land, you can expect that to be even more severe in 2012.
On Thanksgiving Day through the Saturday following Thanksgiving, the crowds decrease quite a bit to what could just be considered "busy" instead of horribly overcrowded and tragic.
The Sunday after Thanskgiving the attendance shoots through the roof again because the AP's are mostly unblocked that day. Your current plan to visit Disneyland the days just before Thanksgiving has you aimed at the highest crowd levels. And again, with Cars Land opening this summer, you can expect those crowds to be even more intense this fall since most APs are blocked out for the summer.
You have to throw out all you know about crowds at WDW when considering a Disneyland visit. If you want to avoid crowds, you need to inspect the AP calendars at Disneyland.com and plan your visit for the days when the Deluxe APs are blocked out.