Rouen vs Strasbourg

Both are good destinations. Just keep in mind very short days in N. Europe at that time of year.

My wife and I loved Rouen for the history of Jean d'Arc and Richard III lying in the Cathedral. A city of grand spires and a trip to the Gros Horloge should not be missed.

Lindsay,

Both are good. It sounds to me that you are yearning for Strasbourg; if so, follow your yearn.

I'll bet you can get a better fare to Strasbourg if you are willing to commit to nonrefundable tickets, can live with second class, and buy from someone other than Rail Europe.

I liked Rouen because it has quite a large medieval center, lots of half-timbered buildings that are hundreds of years old. This is where Joan of Arc was burned at the stake. Now they have a church and square named after her. Rouen is the capital of Normandie and a fairly big city.

Strasbourg is a different feel, more German food and dry white wines. One doctor I met in Strasbourg told me more Germans live there than French.

The Christmas market may be a good reason to choose Strasbourg. Normally, I'd say Rouen is the easier day trip, there are usually plenty of direct trains between Paris and Rouen. I'm not the best at checking schedules. When I look at the train schedule, however (for September, too early to see December), it seems trains are somewhat limited. I think because of track maintenance. I'm not sure if they'll be back to a normal schedule when you visit.

I haven't yet been to Rouen (hope to do so on my current trip) and was in Strasbourg a long time ago, but I think Rick's comment in his guide book is that Strasbourg is the largest city in Alsace but Colmar is the best city in Alsace. (No comparison is being made to Rouen.) I'm currently in Colmar, which is really lovely and small enough to be manageable as a day-trip, though I spent 3 hours at the Unterlinden Museum yesterday. Colmar is farther from Paris than Strasbourg, so I'm certainly not suggesting it to you. But I'd go with Rouen rather than spending substantially more time on the train to get to not-the-best Alsatian city if I had only one day to play with. I think a trip to Alsace cries out for a visit to at least Colmar if not also to some of the small wine towns.

Either way, I'm sure you'll have a great day.

I believe the earlier poster is correct about the fare. If you are willing to buy non-refundable/non-changeable tickets when your planned date initially goes on sale, it appears that a 35€ one-way fare will be available. I also see some trains as low as 25€, but that might be just afternoon or evening trains. I wouldn't want to spend close to $100 per person for train fare on a day-trip, either.

I wonder where you are getting your price estimates. Tickets for December are not on sale yet.
https://en.voyages-sncf.com/en/ shows tickets into September. There is a fairly wide range of prices to Rouen but only two direct trains for a September weekday; the rest require a connection and you must click the Direct Trains button off to see them. Neither of the direct trains is a TGV but some of the connections are.
Strasbourg has a wider price range, often on the high-speed TGVs. One midday service called Ouigo, a rebranding of a previous bargain offer, is only 10 euros if bought today. Except for that one, the prices you quoted can be found but there are others cheaper three months out. All prices one-way.
This is only a guide since there could be changes for three months later. Prices on the TGVs are fluid, tending to rise as the seating capacity is reduced by customer sales..

We did not love Rouen--the old part was worth a visit (and lunch at the creperie near the cathedra very nice). There is a nice museum and shops, etc. The Jeanne d"arc church is skippable. Strasbourg was great! The cathedral probably is the most beautiful I've ever seen. I would opt for Strasbourg and another city I would recommend is Chartres--cathedral there is a must see and the town is charming.

Like our friend said above, you're looking at an overpriced site. Directly on SNCF, buying round-trip tickets to Rouen on the max. 90 day are 20 euros. To Strasbourg, however, are 80 euros. I'll not dictate how each one spend their money, but potentially 100 euros for just a day trip doesn't seems doable for me (although I do have more financial issues, thanks to a weak currency).

A couple of other famous cities:

Chartres: 32 euros
Amboise (a little bit longer trip, but I think it's doable. At least it would be for me): 42 euros
Lille (on SNCF): 30 euros
Reims: 30 euros
Caen: 40 euros
Lyon: 70 euros
Amiens: 32 euros
Troyes: 20 euros
Dijon: 70 euros
Metz: 54 euros
Brussels: 73 euros
Amsterdam: 70 euros (3h30min each way)
Geneva: 82 euros (3h15min each way)

I have not been to Rouen, but I loved Strasbourg (and Alsace in general) when we were there in 2015. We were there at the end of October and I regret not visiting closer to Christmas.

One more vote for Strasbourg.

I enjoyed Rouen quite a bit last summer, but because of the German influence, Alsace is better for Christmastime and Strasbourg has, in my opinion, Europe's most stunning cathedral. Colmar is great too, but for a short trip, you're better off just doing Strasbourg.

Strasbourg.
You have a lot of time to purchase tickets.
Start looking 4 months' in advance. You can often find better prices during off-peak times, such as early morning and during the week.
Keep checking the SNCF calendar of prices.