I'll add my recommendations for the Bayeux Museum, and the Utah Beach Museum (my favorite!!!). I'll add my voice to many who recommend against the Caen "museum" as a waste of time—not terrible, but there are much better IMHO. The airborne museum in Sainte-Mère-Église and the museum at Pegasus bridge are good for their coverage of airborne operations (American and British respectively), although the Utah Beach museum covers this well also for the American sector. The museum in Falaise is good for that sector of the war, but a little off the beaten track. Although there are many smaller museums, I particularly like the ones at actual sights, like the artillery bunker Batterie d'Azeville near Sainte-Mère, or the artificial harbor museum in Arromanches (currently due to reopen after a renovation).
For lunch along the beach, I recommend Hôtel du Casino at the western end of Omaha Beach, where you can sit outside in good weather with one of the best views of this beach. I have also had many a wonderful picnic lunch in my car at various points along Omaha Beach (particularly at the Eastern end) and Utah Beach (NW of the actual landings, but a wonderfully peaceful view of the ocean). There are many good restaurants in Bayeux, but I have eaten in a little place just outside of the entrance to the Cathedral twice (La Rapière?), and both times it was wonderful. For something more casual, Hôtel Reine Mathilde is a nice little place for outside dining if the weather is good. In downtown Sainte-Mère-Église, the Auberge John Steele is a nice restaurant with good food and friendly service. In Sainte-Marie-du-Mont (inland from Utah Beach) is a nice little place called L'estaminet right on the square by the historic church. This is the town where the link up between airborne troopers and amphibious soldiers took place.
Just to clarify, the American Cemetery in Saint James is technically in Brittany, not Normandy. And fairly far off from the D-Day operations themselves. Still, it is a good and humbling cemetery with half the interred, and a tenth or less of the visitors. Other cemeteries I recommend nearer to the beaches are the Canadian Bény Sur Mer Cemetery in Ryes, the British Cemetery in Bayeux on the ring road, and the German Cemetery in Orglandes (not to be confused with the much more visited German cemetery in La Cambre off of the highway). The British have several smaller cemeteries sprinkled through the area as well. And in them, you will often see several other nationalities represented—including Germany, and some nations who don't have their own cemetery in the area. There is a Polish cemetery on the highway to the Falaise Museum.
PM me if you want any more details, and enjoy your trip.