I think one of the most memorable Christmas Parties has to be Australia 1996.
We had only been in our current home for about 4 weeks, we were still knee deep in packing boxes in some rooms - my study especially. We left England on 19th December and arrived in Sydney on 21st December. I will never forget the flight. We flew with a Greek airline because we had had to change our travel plans at short notice as my Cousin who was getting married between Christmas & New Year had, had a change of plans. We had a direct flight, well as direct as 10,000 miles can be, with a stop over in Bangkok for a refuel. Every time the plane landed and took off there was an eruption of clapping and cheering. I put it down to Christmas spirit rather cheering successful flying! I don't recall it being exceptionally cold here that year before Christmas, but we spent 50 hours traveling door to door and left temperatures of approximately 10 degrees centigrade and arrived to about 28 degrees centigrade, and definitely over dressed! We arrived on Stuart's birthday, therefore everyone had gathered at my cousin's house for our arrival which was fantastic.
That year Christmas started on the 19th December and lasted through the arrival party, Christmas, my cousin's wedding, New Year up until we left on 19th January. Very happy memories.