Normandy

Stay in Bayeux; it is a nice town if you want to tour the D-Day Beaches

I would also recommend staying in Bayeux. Wonderful town and great for wandering around. We did a full day tour to D-Day (booked through Viator - but they put us on Overlord tour (Viator is consolidator).
Our guide was fantastic, drove a very modern roomy van and took us not only to several beaches and the cemeteries, but to many of the small towns were significant things happened during D-Day events.

The second day we booked with the same company - same guide for a full day tour of Mont St Michel. Again a great day and wonderful guide.
Several hotels in Bayeux - we stayed in Hotel d'Argouges - wonderful place.

We stayed at the historic Lion d'Or, wonderful restaurant there too.

An alternative choice is Caen, a city rather than a town, and a little closer to Paris on the intercity train. The commute to Bayeux is easy. Caen has a wider choice of accommodations and restaurants, a well-regarded "peace" museum that runs tours to the Normandy beaches and also (for much earlier warfare) the castle fortress of William the Conqueror. Without being asked, I encourage you to pay the big bucks for a full-day guided tour. Anyone except a deeply experienced military student will benefit greatly from the guide's information and context. Those interested in the Commonwealth's part in the landing can find tours slanted that way.

Where does the tour sleep? I've never been on the tour but visited Bayeux, primarily for the Tapestry. If Caen, there is a D-Day museum but also a Norman castle (which would be my personal preference).