Rouen

You don't actually mean the day you arrive do you ! Lol

It would not really be worth it your first day!
Your flight arrives at 11:3o ,you will then arrive in Paris sometime between 1 - 130. Check into hotel store bags there anyways.
Then catch a train to Rouen, if you purchase ticket that day you will pay fill price, bit will not be bound to a certain departure time. If you buy in advance you can get a great deal, bit those special tickets are non refundable so you would have to be careful with timing.

Trains run about every hour or so, and trip takes 1.5 hours.

Basically by the time you get there it would be 4 or so in afternoon, not leaving much time to see things.

I too love the whole Joan of Arc historical thing, but frankly was a bit let down in that respect. However I lovedf my day trip to Rouen anyways. Saw the Tower she was kept in, and the square she was burned in( small rather insignificant !memorial set up) ,, bit highlights of my day was wandering the old town area with the amazing half timbered houses and the numerous shops and cafes. Z

It planning a winter visit keep I'm account I did a lot of outdoor wandering, perhaps not as fun in damp and cold if visiting in winter.

Is it wishful thinking to plan to go to Rouen from CDG airport? We are in our early thirties, so naturally we think we can do anything!

Quite doable as a first stop overnight. Somehow the focus was shifted to day trips rather than overnight, though you did ask where to stay.

Rouen would be a great place to de - jet lag. Nice walkable center full of cathedrals and charm.

Getting there from deGaulle a bit of a chore however, because you have to get into Paris to catch the train. But for jet lag you could drive.

Beautiful city, great for walking around. I spent three nights there a couple of years ago, loved it.

As said you cannot get there from CDG. You have to go into Paris, and then detrain and go to the Gare St Lazare station.
So about an hour ( its more like 45 minites but lets build in ticket buying time,)by train into Paris , 20-30 minutes to transit to other station ( built in a bathroom visit, and if you are smart perhaps time to pick up a snack as you will be hungry and no food service on train to Rouen) then 1.5 hours to Rouen.
Of course if its just a one way trip that day its doable! I would find it tiring but hey, as you point out you are young and strong!
I had incorrectly assumed you meant a day trip as that is basically what Rouen was to me. Oops

Rouen is one of my favorite day excursions from Paris. You can hop on a train at Gare Saint Lazare and arrive in Rouen in about 1 and a half hours. The beautiful medieval old town is an easy walk from the station, and there are numerous places to eat in all price ranges. To save money on the train fare, be sure to buy your tickets ahead of time rather than at the last minute (one week ahead, I think is sufficient). You can buy the tickets online at Capitainetrain.com, a company than I use frequently and prefer to buying directly from SNCF. They have a user-friendly website and excellent customer service (rare in France) and can handle your questions in English.

Booking nonrefundable Paris-Rouen train tickets before you go can save you €10-13 each way, per person in 2nd class. Given the vagaries of flight arrival and transfer to Gare St. Lazare, I'd keep my options open and buy tickets at the train station, no reservation necessary, departs at least hourly. You can get a peak at Rouen at http://www.ricksteves.com/watch-read-listen/video/tv-show/normandy.

Actually you would save a significant amount of money, at least in book, by buying tickets a week ahead. Just for fun I checked the round-trip fare for this Monday, 3 Nov. It was 47 euros total, reimbursable or exchangeable except for a 10 percent penalty.
I also checked w/the same schedule for a week later, 10 Nov. The fare was quoted as 32 euros, same conditions.
To me, that is worth the risk.

michaeljames, I too love Joan of Arc! Last May my husband and I stayed a few days in Colmar and rented a car to drive for 2-1/2 hours to Domrémy-la-Pucelle which wasn't difficult with a gps. The church there is a replacement for the church Jeanne attended but the baptismal font which was used for her is there. The house where she was born and raised is close by as well as a museum of the history of France. It was absolutely amazing to stand in the middle of her house, all alone and realize that such a great person started out right there.
You're welcome to PM me if you'd like to go there and have any questions.

We did exactly that some years ago. We had a rental car waiting for us at CDG and the drive to Rouen was quick and easy. The city itself is relatively small and walkable which made it a pleasant two-night start to our vacation.