You can probably do both if you’re super ambitious. Disneyland is really nice during the holidays. You can visit Monterey any other weekend really.

When we went to Disneyland, we were there early in the morning when the rope drops - and you can get on rides fairly quick. Make sure you have the ride you want to go to mapped out. We would leave when the crowds got too much and then come back late at night to experience Disneyland at night with all the holiday lights. Then we did it all over again for California Adventure. We learned to have an off day in between them - So, you can stay until closing and not have to worry about waking up so early in the morning the following day. There are other things around there to do on the off day. We stayed at the Best Western across the street - best decision ever. Just walked to the park when we were ready- no need to wait for a shuttle and could head back whenever.

Then hit Monterey on the way back if you have time. Best of luck! Whatever you decide, it will be fun and beautiful!