Help me plan my trip to France!

Oh! Another thing, most likely the cheapest way to get to Paris is to look for flights on discount air carriers like easyjet, Ryan Air, etc. and then just start traveling from Paris.

http://en.wikipedia.org/wiki/Saint-Malo is a walled port city in Brittany in northwestern France on the English Channel - beautiful architecture and seascapes, fascinating history, definitely worth visiting.

Toulouse! Amazing, beautiful city. Fantastic food.

My experience of Paris over Xmas was that is was too cold, with most things closed and not much to do except sightseeing in the rain ... but that was Dec 24-26 in the early '80s, so things may be different now.

Nthing Saint-Malo. It's beautiful. Check out http://en.wikipedia.org/wiki/Chartres, a day trip from Paris. I also enjoyed hanging out in http://en.wikipedia.org/wiki/Rouen (Joan of Arc! Monet! Flaubert!) and http://en.wikipedia.org/wiki/Rennes is OK for a day. In general, my fondest memories of France aren't in Paris (except the museums, which are boss), but the mid-sized towns and villages.

Train tickets for the whole journey you're thinking of can work out very expensive, so I'd second the advice above to look at the budget airlines. They mostly specialise in flying out of smaller airports, so there's a good chance that you can fly out of somewhere closer than Barcelona. Ryanair, for example, list over 20 Spanish airports. Some of their Spanish flights are seasonal, and they don't fly to Paris from all the airports listed, but I think you should be able to fly with Ryanair from Valencia or Malaga to Beauvais (outside Paris). Other budget airline may offer flights from Alicante or Murcia or wherever. Flying from Valencia to Paris, and then spending the 14 days touring just northern France would still give you an enormous amount to see. Plan to settle in one place for 3 days over Christmas itself: while only the 25th is an official public holiday, in practice most things are likely to be closed on the 'Regional holiday' of the 26th as well.

Paris over Christmas is much like anadem recalls in the 1980s (hai, I live here). If you are part of a social network or have other friends-of-friends who will take you in for the holidays though, it can be a great cultural experience. Last year I did Christmas in the País Vasco with a family! People saying doing the whole trip by train could be pricy are right! Definitely look for budget airlines, and also consider car-sharing. Check out covoiturage.fr (do most reservations online by bank card, original and biggest site) and covoiturage-libre.fr (pay by cash, an upstart responding to the original's move to bank card and fees). It requires a mobile phone and usually basic French. My friends traveling in-and-out of Spain take the trains to the border (Irun, Hendaye, Perpignan) and then switch. I have taken the trenhotel Paris-Barcelona twice, each time arriving two hours late. There are also buses to Paris from Bilbao (must be Eurolines), and maybe the other cities as well. SNCF (French train monopoly) has recently started their own bus service as well, I don't have any personal experience if the service is competitive/economical: iDBUS. Where to go?? You have a good schedule. Saint Malo is a natural addition to Mt Saint Michel, which you should not miss. Glad you are not interested in the beaches because it will be fucking cold and they are difficult to do by public transport. I have heard wonderful things about Bordeaux (city) and Strasbourg (Christmas markets). Toulouse did not impress me that much. And I always advocate going to Belgium because it is nearby and awesome. Not Brussels, but some of the other cities especially in Flanders.

To my mind, Strasbourg is a little off the track for you (and I love Strasbourg): I agree with Saint Malo and Mt Saint Michel, and would generally suggest that you stick to the west part of France this time (and get back for the rest some other time). Carcassonne is strangely fascinating, on your way up, also please visit the amazing cathedral in Albi, and by all accounts, you should go via Bordeaux on your way back (I haven't been there and feel it was a huge mistake). I loved Quimper when I went there, but I have no idea how to get there with public transportation. Rennes is good too. And yes, most of France is cold and damp in December. Prepare for that.

Thinking further about the weather, if you get an equivalent holiday at Easter, I'd be seriously inclined to stay in southern Spain for Christmas and leave northern France for Easter. Remember that Paris is further north than Maine so the daylight will be very short by American standards.