Paris to St Malo and Mont St. Michel in four days

We just did this in April, but started in Paris took the train to Rennes and picked up our rental car at the train station. The most important part of what you are saying is that you plan to return the car on Sunday. Please make sure you double check the hours of the rental car agency on Sundays. The hours will likely be much more limited than any other day of the week.

As for "given the roads", the roads are absolutely marvelous. So well maintained. Easy to navigate. Although we used google maps, we also had requested that our car had gps, which was extra reassuring. We forgot to ask them to change the language, so our friendly navigator spoke French to us until we finally figured out how to change the language. The drive from Rennes to St Malo is only about an hour and MSM to Rennes is only about an hour, so not sure whey you would need to stop anywhere for the night in between.

Thanks for the great advice, KD. We'll switch our drop-off day to Monday in Rennes, which turns out to be a good thing because it means we'll add 2 nights in Dinan to our stay. Good to hear that the roads are great. We were planning on using Google maps but we'll also request GPS in English. Our high school and college French is way too dusty to survive driving instructions in French. We want to stay overnight in St Malo because of the terrific book All the Light We Cannot See. Our itinerary now looks like this. Any suggestions would be appreciated.

Thursday: train from Paris to Rennes; pick up rental car; drive to St. Malo, stay at Oceania St Malo because it's close to the sites from All the Light We Cannot See

Friday: drive to MSM; stay at Le Relais Du Roy in La Caserne; visit MSM after 5pm when crowds have left

Saturday: back to MSM for early morning visit before crowds; drive to Cancale for oysters then drive to Dinan for two-night stay at Hotel Arvor

Sunday: hop in the car and explore the surrounding area

Monday: drive to Rennes to return car; stay at Citizen M at CDG

Tuesday: early morning flight back to JFK

I have rented a car a couple of times in Rennes, as well as visiting MSM, and Saint-Malo—twice each. Yes, the rental car place may be closed (I forget which days I rented), but often you can still drop off a car after hours. Just take lots of pictures of the car once you park it in case someone else causes damage after you drop it off. Driving in that part of France is easy. Just learn the signs and special rules ahead of time, and watch your speed religiously. There are marked and unmarked speed radars that you might not know about until after you return two months later and get the ticket in the mail (courtesy of your rental car company with their additional fee). Dinan is an easy drive from either city and a wonderful place to stop or stay. You say "four extra days," but does that mean three nights? If so, those Saint-Malo, MSM and Rennes will work great and you won't actually spend too many hours driving unless you want to wander off to other sights. The drive from Saint-Malo or Dinan to MSM is quite pretty.

If it were me I wouldn't be changing hotels every nite. It's a bit of a hassle and also I'd rather not have all of our luggage in the trunk. Break-ins aren't common but they do happen and are more likely in tourist parking locations. Instead of finding another town to stay in why not stay in Rennes one nite, St. Malo for 2 nites, MSM for one? It's only a 1-hour drive from MSM to Rennes.

We used Dinan as a base and visited St. Malo, Dinard, Cap Fréhel, and a few other places, then drove from there to MSM in the afternoon for a 1-nite stay after stopping in Cancale. Most are an hour or so away. You might want to get the Green Michelin Guide for Brittany which will list just about every town in the region a tourist might want to visit.

We spent four nights at a B&B outside of St. Michele (with a view across the pasture of the island) and visited St. Malo, Dinan, and various drives in the area (one from the RS book) from there. We picked up our car in Caen.
If you’re interested, Join us in France does a podcast of the sights in St Malo from “All the Light We Cannot See”. I enjoyed the book so found the sights interesting. https://joinusinfrance.com/show-notes/all-the-light-we-cannot-see-show-notes/

Thanks for that link Renee ! That should be really good, I am looking forward to listening to it.

Adrienne, it sounds like you have a wonderful little mini-trip planned. Enjoy !

This trip report covers more than you asked about, but may be helpful. I'm surprised you didn't mention the D-Day beaches. This is a peak tourism time of year.

https://community.ricksteves.com/travel-forum/france/normandy-brittany-thoughts

We stayed at a B&B near MSM with the idea that the view at a distance was best. We very much regretted it. You can get that distant view but then also spend a night on the island wandering around after the hoards of tourists have left.

You could easily do this on public transport. Go to St. Malo by train and visit places like Dinan if you wish by bus and then take a bus to MSM and return from there to Paris. Getting a car in Rennes does give you more flexibility of course.

https://community.ricksteves.com/travel-forum/france/travel-to-mount-st-michel

Thank you all for your replies regarding our mini-trip outside of Paris. It looks like there's lots to re-think and we appreciate everyone's input. Thanks for the reminder to learn the French traffic signs and rules ahead of our trip. We'll check out youtube videos to prepare. We're happy to hear that the drive to MSM is a pretty one. It'll be nice to get out into the countryside. We would actually prefer not to change hotels but stay in one place as a base so we'll start looking into that. Rennes, Dinan and St. Malo seem equally workable given the short distances between the places we want to visit. Don't want to be worrying about car break-ins on vacation. Will borrow the Green Michelin Guide from the library for in-depth info about the area. Thanks for the link to the podcast about sites in St. Malo from the novel. It sounds like a good one. Thanks also for the links to MSM and Normandy. A few years ago we did an Overlord tour of the D-Day Beaches that was memorable. We originally wanted to stay on MSM but read that the food on the island was terrible and over-priced so we chose a place near the bridge instead that had a decent restaurant. Sounds like the experience of being on the island at night and early morning beats one decent dinner. It's good, too to know that public transport is still doable in the area, especially since we have a four days instead of one or two. Many thanks again, everyone.