We did The week after Thanksgiving last year (2017), and were very happy with the crowd sizes. We found that parks got crowded in the evenings, but were very manageable. We were able to get many day-of fast passes, including FofP and Toy Story Midway Mania 2x in one day. Christmas was in full swing at the parks, and we really enjoyed the Epcot Holiday kiosks. Now fast forward to 2019, and we were really thinking we'd like to do book for the week BEFORE Thanksgiving to try it out. We checked crowd calendars and couldn't figure out why that week was projected to be so crowded..then we remembered STAR WARS!!! So we've ended up booking for the week after Thanksgiving again instead, though this time around, since the holiday falls late, Pop Warner will be going on.
Really curious to see how Star Wars + Mickey/Minnie + new Gondola will affect crowds in 2019.