I would strongly avoid the parks Christmas eve, as they are probably going to be pretty packed. I would recommend dining at O'Hana's at the Polynesian, either the California Grill or Concourse Steakhouse at the Contemporary or Spoodle's at the Boardwalk or the Yachtsman Steakhouse at the Yacht Club. If you want relaxing, then I would completely avoid the parks and any character meals at the resorts. I would also make a PS as soon as you can, as most (if not all) of the restaurants either in the parks or in the resorts are going to be completely booked.