Normandy and Brittany Itinerary

This sounds like a wonderful trip!

You have ten total nights. I personally would move another night or two from Normandy to Brittany, because to me, Brittany is so large that you need more than one home base to do it justice.

We stayed in Dinan last November and found it not only a terrific, historic large town but also a terrific base for day trips to St. Malo and Mont St. Michel.

With more time, I'd add a second Brittany home base further west.

Sent you a PM with a few random thoughts based on our own planning for a trip in September.

I live in Normandie. To help me answer your question

What is your recommended duration in Normandy if this is our first
visit.

It would help to know what you find interesting.

I second the recommendation for Dinan as a base in Brittany; we also used Bayeaux as our base for Normandy. Both worked very well- small enough to easily navigate but large enough to have restaurants, etc to choose from. Both were also well suited as a base for day trips. I might shorten your time in Normandy and add it to Brittany, as there are so many places to visit there. We found a day in Bayeaux and two full days in Normandy to be sufficient (we hired a private guide, William Jordan, who was outstanding and really covered the main WWII sites, not including museums which we did on our own). If you are true WWII buffs you might want longer, however.

The Michelin Green Guides for Brittany and Normandy (2 books) cover just about every town, have suggested driving routes, etc. Also request Stu Dudley's Normandy & Brittany itinerary; see https://www.fodors.com/community/europe/normandy-and-brittany-stu-dudleys-updated-itinerary-1670294/ We used this in addition to the Michelin guide when planning our trip a few years ago. You can also find many videos on YouTube exploring the area.

I’m so happy to see the Michelin Green Guides suggested! My favorites! I’ve used them for years - not as chatty as RS or a travel blog (which I personally see as a positive), but good background and objective reviews.

Second the votes for Dinan also.

5 nights in Bayeux feels a bit long to me, unless you have a deep interest in the D-Day beaches that would warrant visits over multiple days. 4 nights would be plenty, and 3 nights would be sufficient.
And yes, there is more to Normandy than the D-Day beaches, but you'would have to go further east to see the other highlights and Bayeux would not be the right base - not sure you have time.

Conversely, Brittany is large and hard to visit from a single base. If you have ~6-7 nights, then you could spend 3-4 around Dinan and 2-3 around Vannes, then take the train from Vannes to Paris. Do stay in Paris or at CDG airport the night before your flight, though.