Mid November is a nice time of year to visit.
We were there last year from the 8th until the 22nd of November & the MK was decorated for Christmas from when we got there & the other parks were done by the time we left.
Some but not all of the resorts were decorated by the time we left, the Grand Floridian was not done but the ginger bread house was complete, we'd been there in 2012 & flew back to the UK on Thanksgiving day & all of the parks & resorts were decorated by then.
You should also just catch the end of Food & Wine which is good fun & well worth a visit, we spent a nice afternoon wondering round the World Showcase sampling the food & beverage options.
Hopefully the Osborne Family lights will be up this year again at Hollywood Studios, they are spectacular & worth going to see.
You should also consider doing one of the Christmas parties at the MK, they seem to divide opinion on the boards especially when compared to the Halloween parties but we really enjoy them, we did two in 2012 & two again last year & will be going again on our next visit.
If you have any specific questions please feel free to ask on this thread or PM me.