DH and I honeymooned 12/1-12/13, and it was GREAT! No fantastically long lines. We did RnR 3x in a row, and we didn't have to wait more that 5 min. in between rides. We went once, then got a FP, went on RnR again, then used the FP.
It does get chilly, though, and Saturdays in Fantasyland are still VERY crowded that time of year!