Weve been spending Thanksgivings at
Disneyland for the last three years and will again this year. Like you, we always drive because airfare is too expensive and the airports too chaotic during Thanksgiving week. For reference, we live and work in the city.
We always shoot for a half day at work on Wednesdays and drive down immediately afterwards. We pack on Tuesday night and try to have our bags ready by Wednesday morning to leave with us. We do a lot of road trips to Disneyland, and traffic out of the Bay Area always seems to pile up on the 580 by 3 p.m. before a long weekend. Try to leave before 3 p.m. to avoid the worst of the traffic. Weve left as late as 5 or 6 p.m. on the Wednesday before Thanksgiving, and it can take upwards of 2 hours to get from SF over the Altamont Pass onto I-5. Once on the 5, traffic is heavier than usual on the Wednesday before Thanksgiving, but baring an accident it moves. By the time you reach the greater LA area, most of the Thanksgiving traffic has cleared up. The trip from SF to Anaheim usually takes us about 8 hrs. longer if we make a lot of pit stops (we try to limit them to 2) or there is an accident.
With work, our departure is what it is but leaving on Wednesday gets us to Anaheim in time for Disneyland on Thursday morning.
Its the trip back up to SF thats really bad! You figure everyones trying to maximize their weekend but have to head home in time for Monday. Three years ago, we decided to squeeze in a few more hours at the park before heading home and left at 12:30 p.m. We ended up stuck on I-5 for 13 hours because of two really bad accidents. As you know, the 5 is just two lanes through the Central Valley and any accident can turn it into a parking lot for hours. We saw cars pulled over for bathroom emergencies!
We leave for home on Saturday afternoon now. If youre insistent on leaving on Sunday, be on the road as early as you can definitely before 10 a.m. Even then, youre probably looking at 8-9+hours.
Good luck!