From Paris to the Loire Valley, is it worth stopping for a day/night in Orleans? If so, what to do/see there? Thanks in advance!
The Cathedral is rather modern and maybe work a peek, but otherwise so much of it was destoyed. I don't think it's worth it. Chartres, however....or even Vendome...
To me, it would only be worth the stop for a medieval history buff, with the Joan of Arc connection (and even then, the House of Joan of Arc is quite the tourist trap).
It is a pleasant small city where I have been a few times to visit friends, there is nothing wrong with it really, but it just does not have that many highlights. The cathedral is certainly not in my French top-10 (I find it most beautiful seen at a distance, along the perspective of rue Jeanne d'Arc), and I never found the old town to have a particularly distinctive "flair". Other sights (botanical garden in La Source, Loiret riverbank) are much further afield and do not tip the balance.
Chartres or Le Mans would be better bets!
I would spend the time either in Paris or the Loire Valley. No need to spend a night of your hard-earned vacation in Orleans.