I went in late November, first few days of December and basically did Monday at TDL, Tuesday at TDS, Wednesday at TDL and Thursday at TDS ... went back one night the next week (think it was Tuesday) to take the monorail, explore Ikspiari (the TDR version of DD, but much more mall-like) and have dinner at the DLH. The only day that was crazy busy was Monday. Crowds went down every day of the week. On Thursday, basically everything at TDS was under 20 minutes with most things being walk-ons except for ToT, which we FP'd ... I would NEVER visit over a weekend or on a holiday under any circumstances. Also, don't parkhop. It isn't needed. It isn't very convenient. You can't do it on the first two days of any multi-day ticket unless staying at one of their resorts anyway.
The time of year we visited was wonderful. All the Christmas entertainment and decor was out ... weather was also quite nice (60s and sunny, cooler at night). Any other questions, ask away ...