Kev
If it's WWII you're particularly interested in, then Omaha beach, with the US cemetery is a must. Just up the road is Pointe du Hoc, between Omaha and Utah beaches, which was blasted from the air and sea, and has been left as is. Further north is St Mere Eglise, where they still have a 'parachutist' hanging from the church steeple. There's also a museum there, and another at Bayeux.
If you want to stay around the Bayeux area, I can give you the name of a good camp site that also has gites - they will also feed you with solids and copious quantities of calvados!!
Del