By the thread title I thought that you were going to be at Disneyland over Christmas or at Christmas time. I was surprised to open up the thread and see that it's a trip starting on January 6th!
I'm not sure how long it's been since you were last at DLR for the holidays, but if you take a peek at the
Disneyland at Christmas/Holiday Season Superthread (scroll down through the info/photo posts on page 1 of the thread), you might notice if there are any events or things that are new since you were last there. Please free to pop in over there and ask us any questions as well!
In addition to what
figment_jii mentioned above, the Grand Californian Hotel has a large gingerbread house in the lobby that is supposedly going to come down after 1/6/15. I am not sure when the smaller gingerbread houses in Storytellers Café and White Water Snacks come down. Also, there are decorations at the Disneyland Hotel (that were new as of 2013) and if they are still up on 1/6, you can bet that they will come down as soon as 1/6 is over.
I am guessing that the Jingle Jangle Jamboree will probably be closed after 1/6.
Beyond 1/6, Haunted Mansion Holiday looks as though it will be open through 1/11 this year, and It's a Small World Holiday should be open through at least 1/23, if not a couple of days beyond.
Olaf's Frozen Ice Rink and the Winter Village in DTD will be open through February 22nd.
"Frozen Fun" officially kicks off in Hollywood Land in DCA on January 7th, but some of it will be open as a sneak peek prior to 1/7.
Most of the holiday decorations in both parks, at the hotels and in Downtown Disney will probably start to come down right after 1/6 (if not slightly before).