Sorry, don't know why I was thinking Christmas. The week after Thanksgiving could end up being the same weekend as Candlelight Processional. That could be either really nice for you if you want to view that, or really difficult because the front of Main St gets so crowded and jammed. It is extremely difficult to get in and out of the park during that event. If you are there for a full week, you probably won't care if you can't get into the park easily on those afternoons/evenings because you will have lots of other time to get through there. Also, maybe the monorail will be in easy in/easy out.
Personally, I really like the week after Thanksgiving. It's not too crowded at that point and everything is normally running. I do avoid Candlelight Processional days, though. I was stuck once in when trying to enter and then again when trying to exit and decided never again. I've seen others post that they get in early and stay away from Main street for the rest of the day, so that's an option.