If the choice has to be between the two (neither would be my prefernece), the I would pick Christmas. November is about as dead in Europe as can be. Many hotels, resorts, etc are closed. The owners are taking their own vacation relaxing somewhere exotic in the sun. Christmas gives you a chance to see some Christmas markets, there are more tourist activities, etc.

We spent Thanksgiving in Paris in 2011 and Christmas in 2010. Both were great. We had snow at Christmas but many say Paris doesn't usually get alot of snow. The store windows are great, as are the markets. The one on Champs Elysee was open at Thanksgiving, but crowded and I like the smaller ones in neighborhoods.

One great thing about Thanksgiving, is far fewer crowds, especially at major attractions. We had no issue with anything be closed in late Nov. in Paris. We had good weather. No guarantees on the weather, and you will be fine if you layer. I wouldn't choose the time based on the weather.

We preferred Christmas to Thanksgiving (slightly) but both trips were great. You can click on my name to find the T/R for both trips and get links to photos

Paris is not too shutdown at Christmas....yes, Christmas Eve and the earlier part of Christmas Day. There are things that are open, so no problem. You can hit the " non-Christian" parts of the city to find more open on those two days.

Many have stated here that London really shuts down at Christmas.

Christmas would be more festive (obviously haha) and there would be more going on. You'd probably spend a whole lot less money in November, though, as that would be the quiet season.

I think it depends on what you're planning to do. Austria or Germany would be lots of fun at Christmas time, and I'm sure any big city would be. So if you're enthusiastic Christmas people, maybe that's your best bet.

On the other hand, Paris is probably awesome no matter when you go! And I'm sure London is too. If you stick to big cities, there's always plenty to do no matter what time of year you go, in terms of dining, concerts, museums, etc.

I don't necessarily agree that November is dead in Europe, but it will certainly be quieter and there will be fewer tourists. But who knows, you might find that suits you better

I also don't agree that Europe is "dead" in November. I've been many times (mostly Paris, but also Prague & London) and there are blissfully fewer crowds, but I never came across anything that was closed (outside the normal weekly closures). Sorry, I haven't been over Christmas so I can't compare. I do think you're more likely to get better deals in November, soley based on increased tourism around Christmas.

It would concern me that I've read so much about how much of London is closed around Christmas.

We were in Paris over the same Thanksgiving as Denise above, and loved it. We only got to do the market on the Champs, and I'm sure other Christmas markets would be fun. The food markets were open and thriving.

But are markets of that much interest to you? If you are interested in museums and galleries and historic attractions, I can tell you that Thanksgiving was a terrific time to visit these places.

I can't speak for London.

As someone living/working in London and who travels to Paris frequently, I can attest that certainly neither are even close to "dead" in November or December. I do love both cities around Christmas just due to the festive feeling, holiday lights, markets and other holiday events (such as winter fair at Hyde Park,etc) so I would lean towards Christmas if it is all the same to you otherwise. It is definitely higher probability of colder weather in December (sitting with snow right now in London although this is unusual)but not worth making a decision over as it will come down to luck of the draw on weather anyway.

Depending on how long you stay past Thanksgiving, you might benefit from the holiday lights, and christmas markets even in November as many open at end of November/early December. We may not get the Thanksgiving holiday here but the Christmas "season" starts about the same time!

If you find yourself in Paris on Thanksgiving, and need a can of pumpkin or cranberry sauce, pop on down to Rue St Paul in the Marais: www.thanksgivingparis.com/
Also could take care of your Duncan Hines cake mix and ReddiWhip needs, too, probably.

Paris is magical at Christmas, though chock full of tourists and high season for rentals.

We found both London and Paris amazingly mild between Dec. 23 and Jan 11 this year. Grey, often, yes.

Well over christmas a lot of things will be closed for 1 or 2 days - while Thanksgiving everything will be open. Weather probably a little warmer in Nov - but none of these places in really cold (as in northern US cold) except for very rare days.

Today's high in NYC is 22 - VERY rare in any of these places. Weather more like DC or VA chilly but not bitter.

Be aware that heating indoors may not be what you are used to in the US.

I'd come in November as there is no festival in France or UK during the period you describe. Hence, everything will be open but the Christmas prep. will be well started. All the pleasure and none of the problems.

London has no transit on Xmas day, but other than that it is very festive and open! You may have some things close early on Xmas eve, but that happens in Paris and other places as well. You just need to plan around Xmas day if you are here on Xmas day.

Paris does have transit on Christmas Eve and Christmas Day. It is supposed to be limited but we had no problems getting around on the Metro. We didn't find Christmas day to be dead at all and we had plans on C Eve, so no problems. I would go back for either holiday!

I wouldn't worry too much about many things being closed on Christmas Day, as long as you are in a central location in London. Boxing Day (Dec 26th) is also a public holiday, but many sporting events take place, and that's when shops usually start their post-Christmas sales. You might pick up some bargains.