Not any ordinary day trip from Paris

I have enjoyed daytrips to Rouen. It's a walkable town and has that magnificant cathedral. Also, there are lots of restaurants and other places to eat. The church and grounds memorializing Jeanne D'Arc are centrally located and worth a visit. It's easy to get there by train and the trains run frequently. Chartres is a good daytrip if you want to see the cathedral.

I really enjoyed my daytrip to Rouen,, but... it was in the summer, when it was warm,, so spending hours wandering about was pleasant, many shops, cafes, the medival half timbered houses,, Joan of Arcs square,, all wonderful, but thinking maybe not so wonderful if its cold or rainy.. Its a bit of a walk from the train station to where the sort of central touristy part of Rouen is,, but, as I said, lovely to wander, in summer, for winter,, er not for me.
That said, I would try and find somewhere that has a few indoor activities ( the church in Rouen was a 1/2 hr visit at most) so that if its pouring or freezing you still can have a fun busy day. I may just be a wimp though, I am freezing right now and its only like 6 ( celicus)or something,, I want summer!

I seem to always agree with Pat. Bad weather can make some day trips less than fun. We were in Rouen in July of 2010 and it was in the high 90's, extremely high humidity, raining and dark. We did not enjoy our time there. My favorite day trips, other than Versailles and Giverny, are Fontainebleau, Vaux le Vicomte and Malmaison. No matter what the weather is.

Susan,, too hot would be as bad as too cold,, and that sounded way too hot and humid for me too! Walking back up to the train station would have been hard!

I am going to say Fountainbleu, and I notice Susan said that as one of her choices. I loved our day trip there!

If you're going in December you could do an overnight to Strasbourg or Colmar (they're a little far for a day trip). I know Strasbourg has a Christmas market and Colmar may also, that might be fun.

Although not a long day trip (and definitely not an overnight) I'd recomend a visit to Vaux-le-Vicomte in December. The chateau is decorated for Christmas and it really is beautiful. Colmar/Strasbourg could be a good overnight trip for the Christmas markets. I don't recommend Chartres. I think the people that recommend it haven't been there lately. Over 1/2 the interior is covered/blocked off by scaffolding and is expected to be there a long time. My very religous father went there as a pilgramige (not just to see a pretty church) and walked away declaring it wasn't worth the time. You just can't see enough of the stained glass windows, you can't get to most of the chapels or even close to the altar. Huge disappointment.

Thanks everyone, I appreciate the great suggestions!

Pat, you're so right, walking the long way back to the train would have been really hard in that heat and humidity since it's all uphill. We decided to take a bus - which we waited a very long time for (you never know when they're coming). Got to the train station within minutes of catching the train back to Paris only to find out no trains could leave cuz a train on that track had broken down and they had to wait for it to be removed. No one could say how long it would take. We waited for 3 hrs, every minute not knowing when, and meanwhile, the station kept filling up with people wanting to go to Paris. When the train finally came, a massive crowd of people raced and pushed their way to the train (us included - we were afraid the train would be so full we wouldn't get on). We got on, but we were all packed like sardines on that train back to Paris. Needless to say, I do not have fond memories of Rouen! Not Rouen's fault, I know, but still...

I've been told by people who've been to many that Strasbourg's Christmas market is one of the best. Plus Strasbourg has a couple of great museums if it's too cold for a lot of wandering.