We had a week in London, which of course is about enough to see a thousandth of the city =)
Hyde park winter wonderland - a huge german-ish christmas market- was lots of fun (as long as it was during the week - Saturday was a bit mad!). The markets at South Bank were gorgeous too.
My (current) very favourite parts of London are St Christopher Place and Covent Garden - we spent quite a bit of time at each, and they both had killer christmas decorations up =)
Actually seeing everywhere decked out for Christmas was one of the best things about having been there at this time of year - I might have to do a separate blogpost rounding up some favourites =)