I just got back from a week's stay Nov. 10-17. The 17th was the Saturday before Thanksgiving. In terms of crowds, the were very low and quite manageable in MK, EPCOT, and MGM (we didn't go to AK). We even went to
MVMCP and the crowds were not as bad as we expected.
We like to go this time of year because its low season and the parks are fairly empty. We walked on to most rides. You get the benefit of having the holiday decorations and MVMCP. The only downside we're encountered is that the parks close early, about 6 or 7, depending on which one. We've always rented a car and used the evening hours to go out to dinner or do some holiday shopping.
That time of year is also Super Soap weekend, Food and Wine festival, and Jersey week, so you may want to check out those dates before you commit to yours.
Temps not being an issue, but packing may be. We had warm days, but chilly evenings, so we ended up carrying a sweatshirt around most of the day and putting it on at night. We also packed jeans and shorts, so it made packing a bit trickier.
Another downside was the Saturday we left, MCO was CRAZY. Lots of people going out of town. But if you give yourself some extra time, that's really the only minus to travelling to WDW the week before Thanksgiving.
Good luck with the planning!