For the WW2, the Day landings have a look at
http://www.junobeach.info/ From Ouistrem - largish town, depending on the time of your visit, could make a good base - west to Arromanche there is a great deal to see.
Due south to Benouville is Pegaus bridge, the first objective to be attained on Day, lots of stories about the gliders, capturing the bridge itself and liberation of the first building, the Cafe Gondree. A small museum lays out the sequence and reasons. You will pick up pointers to quite a few other strategic objectives, river crossings, blockhaus and gun emplacements which could have derailed allied plans
Back to the coast and Courseulles sur Mer which was the centre of Juno Beach, and another first building liberated, first by sea bourne forces - yea the Canadians! You will recognise it because it is the one in all the newsreel clips. There is a blog somewhere by some guys doing the visit.
As you approach Arromanches, on the top of the cliffs before you drop down into town, there is the Arromanches 360, which shows a montage of documentary, re-enactment and video of the places where actions took place. Very moving, powerful and give a real sense of time and place.
Into the town is the Musee du Debarquement which gives a great view of the overall invasion, then focuses in on Mulberry and the more local events. If the tide is out a walk out to the remaining caissons is recommended. If you haven't heard much about the Mulberry, then a bit of homework will give some perspective.
I lived quite near the town of Corby, where the steel pipe for PLUTO was designed and made. PLUTO = pipeline under the ocean. Huge quantities of fuel for all the vehicles was pumped through this small bowser. AFAIK, no trace remains.
Continue west to Bayeaux, which was the first sizable town/city liberated. It also is home to the Bayeux Tapestry. Made in the 1080's, it documents the story behind the Norman invasion of England and the Battle of Hastings and the forging of not always amical relations between the to countries of France and England.
Beyond to the west is the US sector of Omaha and Utah, worth a visit if you haven't been before.
Back to the east of Ouistrem, and you can use some nice roads across rural Normandy, Caen is a decent sized city now, but with plenty to see, but also the bustle and difficulties of trying to do these places on a short time scale. However the Le Mémorial de Caen is worth it.
There are so many other places of interest in and around Normandy, it really just depends on what you want to see or what your interests are.
Using smaller roads will make the whole riding experience nicer too. Motorways are uninteresting and the larger N roads, the trunk roads, can be boring and full of traffic.
Many towns and villages have had by passes built, but then of course you miss all the historic places and just see fields, I almost always take the Centre Ville sign.
If there are artistic or garden lovers in the party then a side trip to Giverny, to see Monets garden is well worth the detor.
The defining moment for Canadian Forces in WW1 was the Battle for Vimy Ridge. The courage, determination and sacrifice of the Canadian Corps at Vimy led to France giving the land on which the battle was fought to Canada in perpetuity. The visitors centre is manned by Canadian Students who take you on the tours of the Grange Highway - the vast underground labyrinth which played a significant part in the operations success. Trench lines have been maintained so you can see the proximity and relationship of one side to the other.
Vimy is close by Arras. As well as the "old" town, the quotes are because it was shelled to buggery in WW1, had just been rebuilt and got shelled again in WW2. Once again, it has now been rebuilt to its former glory - well worth the trip. Nice town for a wander, especially if you can get there on market day - that applies to most French villages, towns and cities - IIRC on Saturdays? for the biggest one
Arras has a large Vauban fort (Vauban was an interesting guy, what we would now call a sapper/military engineer, and humanist) he designed well over 100 forts to surround the French borders at the time of Louis 14, all characteristic of the "Star" fort.
If you follow the signs "Citadelle", on the Boulevard de General de Gaulle,you come to the distinctive CWWG. There is easy parking. Following the path, you arrive at the Mur de Fusilles, where the gestapo shot many members of the local Resistance.
In France, there is always an better - usually much better - alternative to autoroutes. A few minutes look at a real map, will give you some ideas of the roads which are likely to be more interesting. The map lets you see the "big picture" away from the "shortest, quickest" algorithms.
Yellow roads are "D" roads. D for Departmentals, ie the responsibility of the locals. These will more often follow the lie of the land and be the result of eons of people and animals going about their business of making nice routes for us to follow along. Almost certainly less traffic, almost certainly more picturesque, almost certainly bereft of policing - although take care, the fines for excess speed are quite high and are definitely "on-the-spot", "take me to your ATM" sort. Real excess speed can apparently result in your vehicle being confiscated.
In case that all seems a bit heavy, the French, along with most other Europeans (possible exceptions being here in UK) are usually very friendly, welcoming and understanding towards bikers. In even high class joints.
Michelin regional maps are usually available in supermarkets or librairie (bookstore) Usually yellow and 1:200,000 scale. The relevant numbers on mine are Normandy = 231, Nord = 236. A red 721 national map at 1:1,000,000 can give a good overview for liason stages, or seeing if it is possible to pull in something you just heard about. Online too of course.
Have a great time.