We were in the parks last year Wednesday, Thursday (Thanksgiving), Friday, Saturday and Sunday. I really enjoyed being on the park on Thanksgiving day. I don't think it was empty, it was still crowded but less crowded than Wednesday and Friday. We had a Blue Bayou reservation for Fantasmic Package for dinner and it was fantastic. We saw the late showing of Fantasmic and there were very few people in our section. Very nice!
Also, this year we are AP holders and as the previous poster said - we are blocked the end of the week (Deluxe is blocked Thursday, Friday, & Saturday) whereas last year we were on our 5-day park hopper (upgraded second to last day of the trip)
We were just in the parks last weekend (October 14, 15, 16) and it felt just as crowded as Thanksgiving time. Probably due to the lack of the
Disneyland Railroad, Rivers of America attractions, and Critter Country being closed.
That being said I would do Disneyland on Thanksgiving day again in a heartbeat! But alas we're blocked so we'll be in the park with the crowds on the 19th & 20th. Honestly, it's always crowded - so get there early, plan your FP pulls, and enjoy it.