Have a bimble around the Contentin - Avranches, Granville, Coustances, Carteret & along the coast to the Nez de Jobourg. Then cut back east to Cherbourg & on to Barfleur, then south to St.Vaaste-la-Hougue (boat mad here, nice overnight). Then carry on south along the coast to pick up the Normandy Landings story, staring at Utah - take an excursion inland to see KM1 & the museum at Ste-Mere-Eglise. Then back to Carentan, Isigny & along the coast - Point du Hoc, Omaha (war cemetary), Gold beach Arromanches (museum), Juno & Sword beaches, then after Riva Bella, follow the Orne river inland to Ranville-Benouville & Pegasus Bridge. Then back to the coast, Deauville, Trouville & Honfleur (very lively on market days & a good ON).
Then a possible detour to Rouen, or over the bridge to Le Havre, Etretat, Fecamp (nice ON), Dieppe, Le Touquet PP. & back to Calais.
That should keep you busy. If the D-Day landings are of interest, Michelin do a green guide devoted to the subject.
Others may disagree, but bike/gear theft can be a problem in La Belle France, so take the obvious precautions & try to get Garage/secure parking overnight where possible.
Have a good trip.