Thanks! We thought of Bayeux, but we've decided in the end to look for a farm B&B in the Manche area of Normandy for one night; the second night will be either in, or very near Mont St-Michel. In fact, if there are no reasonable rooms available on the Mont, and if the B&B is near enough for us to spend the evening on the Mont, we might take the second night there.
I've been advised that the experience on Mont St.-Michel is very different after the crowd leaves, so we'd like to stay for at least a late-ish dinner.