Do any of the chateaux in the Loire Valley offer overnight accommodation
There is a small chateau near Loudon which offers vacation rentals. Chateau de Nue is not a big glamourous chateau in the Marie Antoinette sense of the word, buy it is a chateau and is very pretty.
This website lists castle (chateau) stays in France. Looks like some in Loire Valley. Maybe a bit pricey but castle stays usually are.
We are in Paris now. We stayed in 2. Near Fougeres ( not the Loire) was called Chateau du Bois Guy. Loved it. It was my choice.
Second was Domaine de la Tortiniere near Tours. Gorgeous. Loved it. Great service.
In the Loire, I've stayed in Chateau d'Artigny, Chateau Chissay, and Chateau du Pray. All were unforgettable experiences.
You will feel like Royalty in either, though d'Artigny was my favorite.