The Cotentin Peninsula is a delight and a joy. I had a couple of very happy holidays there in the noughties, one based at La Haye du Puits and another at Barneville-Carteret. Although both were avec les enfants and not cycling holidays as such, significant amounts of cycling was done in order to escape from said sprogs. (and drinking cidre, brown beer and calvados and eating far too many dairy products)
Most people scream south from Cherbourg as fast as their company car will carry them and stick only to the main roads. Slow down, ease up and turn off and an undiscovered part of France awaits, a France of small towns that foreign tourists don't visit, of dairy farms and degustation, or bread and cheese washed down with beer, of cidre that makes your knees buckle, of quiet beaches, and, oddly, lots and lots of English history.