I have some flexible days to work with on my family trip and am trying to decide whether to take a day in Rouen or Le Mans/Chartres. Any suggestions about which you would prefer and why? As I have been to neither it is difficult to determine which we will enjoy the most. Our interests are historical sites and of course good food, but we also love just meandering through interesting towns.
I lean towards Le Mans and Chartres, but it depends on the rest of your route.
Why Le Mans and Chartres? Because Le Mans is blissfully un-touristy yet very striking, with a better-preserved medieval town centre than Rouen, and none of the industrial blight that greets you there when you arrive by road. And Chartres has of course the cathedral, but also a pleasant town centre, full of life with many shops (this is also true in Rouen).
However, it is ambitious to visit Le Mans and Chartres together in a single day. If you have 2 nights and can spend another 1/2 day in Chartres then OK.
If you can combine Chartres and Le Mans, it would to my opinion to prefer above a single trip to Rouen. The historic centre of Le Mans has a surprisingly natural feel making it very attractive, but that's my idea.
Several years ago we visited the cathedral in Chartres and wandered around town afterward. We arrived late morning so pretty well had the place to ourselves. It was a worthwhile stop.
Le Mans and Chartres are on the same train line, but I wouldn't call them "close" for a day trip. Both spectacular cities and deserve their own day. I lived between the two in a lovely village called Nogent-le-Rotrou ---a city who has her own amazing chateau and is the capital of the Perche region. Green, green, green.
I, on the other hand, find Rouen captivating. The little ruelles near the Musee Jean d'Arc, all the amazing churches and restaurants. It's actually one of the smallest cities in France to posess a metro (which is nice because it is an uphill walk to the gare)
Haven't been to Le Mans but have been to Rouen and Chartres. We enjoyed Rouen, walking down the pedestrian-only streets and visiting the Cathedral. It would be my vote for where to spend a day. It is also the city where Julia Childs had her memorable first meal in France if you're a fan of the movie "Julie and Julia" and the actual restaurant is still there (serving a very expensive replica of her meal, too). If you visit Chartres don't go on a Monday when almost all the shops are closed.
Oh, that is good to know because Monday is the day we would be there.
To throw out one more city in the general area of these others, how about Rennes? It has a sizeable student presence (at least it did pre-Covid), pedestrian-only streets, nice parks including the Thabor gardens, small but interesting museums, and half-timbered houses galore. It's about 90 minutes from Paris on the TGV.
Yes, I do not think that there will be much difference in the % of open shops in Rouen, Chartres or Le Mans... granted, I have not been in all three on Mondays. But I wouldn't change plans just because it is Monday. Not a deal breaker in my opinion.