If you're planning a trip to Normandy and staying in Bayeux, I highly recommend looking into Bayeux Shuttle for visiting the D-Day beaches.
What I particularly like is the flexibility. You can visit the major American sectors such as Omaha and Utah, explore the British and Canadian beaches, or combine the beaches with places like Sainte-Mère-Église and the Airborne sector.
For us Americans, having a knowledgeable English-speaking driver/guide makes a huge difference. The distances can be deceiving, and there is so much history hidden behind what you see on the surface.
Bayeux is also a much better base for exploring the Normandy battlefields than trying to do everything as a day trip from Paris.