Brittany and Normandy

You haven't mentioned what sort of sightseeing interests you, but--in addition to the places you've already mentioned--I enjoyed seeing Vitre, Rennes and Dinard in the area not too far from Mont-St-Michel. I found St-Malo extremely crowded, but many people like it. I wonder whether the immediate area around Mont-St-Michel (Pontorson?) is the best area to use as a multi-night base. I haven't been to MSM, but I'd expect lodgings near there to be a bit overpriced. Perhaps not if everyone just daytrips there.

Farther east, I liked Rouen a lot. Bayeux has worthwhile sights in addition to being a good base for seeing invasion sites. Most of the D-Day van tours originate in Bayeux.

On and near the southern coast of Brittany, I though Vannes and Quimper were both worthwhile. I also liked Nantes, which has been realigned out of Brittany but is a Breton city (and rather large).

Stuttgart to Brittany is not easy. The best way is to take the train, via Paris, to Rennes or Nantes.

You need to buy the Michelin green guide for the sites/sights in Brittany. There is a lot beyond Mont Saint Michel, St. Malo for you to choose from. Finisterre, the coasts, enclosed churches. In July you could run into local festivals or religious processions.

Several years ago we enjoyed spending 2 nights at Les Valtières du Mont-Saint-Michel - https://www.montsaintmichel-location-gite.fr. We also drove over to the delightful little seaside town of Cancale at the edge of Brittany. In Normandy, the coastal town of Arromanches-les-Bains was fun with the remnants of the WWII mulberry harbour and the german gun battery complex at nearby Longues-sur-Mer was cool.

The French airline Volotea has direct flights from Strasbourg to Nantes for about $25 one way.

Maybe Zurich has seasonal flights to Bordeaux?

I would buy Lonely Planet France to plan the on-the-ground. If you post again, be sure to tell us you are renting a car? This is peak beach season, so the coast may be crowded, and advance purchase rooms important. When we stayed in Dinard (just for example) we made sure our hotel had (fold-up padlocked stanchions) reserved parking nearby.

The Tour de France bike race is a major event in French history and culture, and seeing any of it in person is a big opportunity some never get. This year, although the whole race actually starts in Denmark, the July 5 stage starts in Dunkerque (Dunkirk) and finishes in Calais. OK, so those aren’t technically in the Normandy Department, and are quite some distance from Bayeux and Utah Beach, but still on the northern coast, and with history. And the Tour only heads south from there this year, so it’s your closest shot.

Oysters in Cancale are a treat. July 2008, coming from Belgium and heading to Saint Malo in Brittany (to see some of the Tour that year), we pulled over to an oyster shack at the side of the the road and the edge of the ocean for fresh, just-harvested oysters.

Farther west along the northern Brittany coast is the Côte de Granit Rose (Pink Granite Coast) with fantastic pinkish rock formations. A hike among the unusual shapes and colors is a unique Bit of Nature experience. It runs for several miles. We stayed a few miles inland from the amazing walking, in Lannion.

Eight years later, and also with rental car, we had a couple nights in Pont-Aven, which was long an influential location for Impressionist artists. Small town, worth visiting.

Quimper is also highly recommended. Its old town is a contrast with other parts of France. Reflecting the Celtic culture of Brittany, there’s an annual festival each July, but you’ll miss it by a couple of weeks. Still, seeing Quimper will let you get a taste of the scene. The indoor food market is fabulous.

Speaking of tastes, in Brittany, be sure to have a Galette, a savory buckwheat crepe. And Kouign-Amann (pronounced “queen ah mahn”) - it’s like a buttery giant caramel roll on steroids.

I would extend your research well outside of Rick Steves. He tends to have minimal info on these areas IMHO, and last I knew, didn't even cover the Utah Beach area. Bayeux is a good base, but if you are interested in Utah Beach, it is a little bit of a ride. Sainte-Mère-Église is a fun little town near Utah Beach, but with much fewer dining options in town than Bayeux. But there are a couple additional options in neighboring towns (I have dined in Saint-Côme-du Mont, Sainte-Marie-du-Mont, Carentan and Ravenoville, as well as the wonderful Auberge John Steel in SME itself.).