We did DC on Christmas Day 3 years ago. We were at the Residence Inn at SW. We went to wash up and change in our room at the end of the day. We stayed until park close. Then we had a 7:30pm reservation at Margaritaville. I was very very thankful for the reservation. Since I have an AP, we parked in the CityWalk garage, and walked into a thick sea of people. Since I am familiar with CityWalk, I lead my hand held family chain parting the crowds like a fish. It was a great meal, festive and fun. We then wove our way back to our car, then drove back to our hotel, that was not that far away, just took time because of the traffic.
Since you are at RPR, I would look at that hotel resaurants. Once the parks are closed in Universal, the masses clog CityWalk. Since Toothsome will be officially open on the 22nd, I would keep looking for a reservation after that. Since not all the Universal restaurants have a uniform time on first time you can reserve. I think I made mine in October, but I will look and see if I still have the email confirmation. I will look for ya, and post if I do.
We enjoyed our holiday at DC so much, we are returning to it again this holiday. If you would like to say hi, we would be happy to do a DIS meet.
Have an awesome time! And jealous you are at RPR.