We were there last year 20th - 27th nov. We had a fantastic time.
We stayed at Homewood suites Anaheim convention centre which gave us a seperate bedroom a living area, kitchen, free breakfast and a free evening meal on select nights of the week I think it was mon - Thursday. You walked next door to the toy story parking lot and caught the bus to the park. Not sure if you have booked accomodation yet but it was great with teens.
Try to be at
Disneyland for a weekend fri night - sun night as some of the night time events such as fireworks or parades are only on weekends till after thanksgiving or December. If you plan to be at Disney on thanksgiving see if you can book the thanksgiving buffet at Disneyland hotel. It is expensive but for our first thanksgiving and probably only it was a great experience.
We did not enter the parks on thanksgiving day. We went to the buffet, a movie at downtown Disney Moana and played some games at espn at down town Disney. Had a great time.
We also got to see the Christmas parade which I think started the weekend before thanksgiving.
I found the parks to be ok crowd wise on the days leading up to thanksgiving and the weekend before. The Friday and Saturday after thanksgiving in regards to crowds was terrible.
We had planned to go on the Friday in the morning before our other activities but got in the que and gave up.
Went back to our hotel had a swim( it was warm enough last year) then went to an ice hockey game in the afternoon before ending the day shopping at the Black Friday sales.
We actually stayed in Anaheim the whole time and did tours from Anaheim to la to do things we wanted to do. I hate having to waste a changer over day if they won't let you check in till 4.
I am the type of person who likes to get a base and travel from that spot.
With it being a busy time sometimes it is easier to book for example the dessert party with WOrld of colour.
There is a thread on the Disneyland forum that talks about all the Christmas activities. Have a read of it as it has some great ideas.