Hi, John!
A trip to the Disneyland Resort in December sounds fabulous! I love going to the parks when they are decked out for the holidays. Mickey loves Christmas and starts
decorating in November, so the parks will be in full swing with all the
festivities and décor when you arrive.
Park hours are not listed yet for December.
Keep checking the calendar for updates. While hours are subject to change, last year Disneyland Park was open 8am - midnight and Disney California Adventure was open 9am - 10pm during your travel dates. You can use these times as a general guideline, but again, remember those were 2016 hours so those are just an estimate for 2017!
There will be plenty of nighttime magic during your stay, including
World of Color - Season of Light at Disney California Adventure Park. This will put you in a holiday mood and have you humming festive tunes the rest of the night!
Wishing you a magical vacation and happy holiday season in the Disneyland Resort!
Cathy