Britany and Normandy 4 day itinerary

Here is a link to my detailed trip report from last year, including Bayeux and Rouen, both of which we loved. Maybe it will give you some ideas. https://community.ricksteves.com/travel-forum/trip-reports/france-rouen-bayeux-and-amboise-so-far

Here are some snapshots of our 5 nights in Normandy.

https://janettravels.wordpress.com/category/normandy/
We also did an all day tour of the American beaches with Overlord on one day which is not pictured here. Alas our trip to Brittany this fall was cancelled when I broke my elbow in the south and needed surgery -- we had to either drop the Ardeche or Brittany when I was delayed 5 days and we chose the Ardeche and the Caverne du Pont d'Arc.

We did Rouen as a day trip from Paris at a later time and found that also quite interesting.

Normandy is large and Brittany is huge; do you have any ideas about where you want to visit (cities or towns) or what you want to see (D-day landing beaches, Mont St Michel, etc)? 4 days are not very long. Where would you be coming from and going to before and after these 4 days? Driving or using public transport?

It's really about what you are interested in. Druids, Normans, WW2, MSM?

I agree with Nancy's comments above. Four days is not much time for either region, let alone both. I would pick one and then focus on meaningfully enjoying that area. We spent 7 days in Upper and Lower Normandy two years ago, and even that didn't seem like enough time.

Only 4 days for both Brittany and Normandy means that you should concentrate only on the "entrance" of Brittany, for example along the north coast of Brittany, near Mont Saint Michel : Saint Malo, Fougères, Rennes, Dinan, Dinard, Vitré, Combourg, etc.
For a further trip to Brittany you could reach the south and west part of the region, which is also well worth spending a week. You may get some ideas for your itinerary in Bretagne on http://visite.bretagne.free.fr/index.php/en/itineraries.html

Two other interests to consider in your limited time are cider manufacturing and public gardens. I don't think you said whether you'll have a car. You might be able to minimize the massive amount of time many visitors allow for the D-Day beaches by reading a guidebook (like Rick's for instance) to determine what you really want to see. Transportation is especially important to your experience there, especially in peak travel season. The narrow roads can be crowded, and the parking lots full, even if you have the freedom of a car.

I have to completely disagree with the previous post. First, most people post here that they wish they had more time in the Normandy Beaches area, not less. Second, I have visited this area on the anniversary of D-day four times (a fifth coming up this year) and one more time in the summer (not on an anniversary). Not once have I found that the "narrow roads can be crowded," or "the parking lots full." In fact, one of the things I like about this area is how accessible it is, and how easy it is to get around to see the sights whenever you want. Only in 2014 (the 70th anniversary) were a couple of key locations blocked off for foreign dignitaries for a limited number of hours on June 6th itself. But the area is so large that there were so many sight to visit on that day—including the Sainte-Mére-Èglise area which is the epicenter of the D-day anniversary commemorations.
My too sense...