1 week to visit the Loire Valley and Mont Saint Michel suggestions please

The Navigo pass covers public transportation within Paris, as well as the RER trains to the suburban areas. It will not cover your trains to other areas.

A frequent recommendation is to take the train to Rennes and pick up a rental car there. Drive to Mont St Michel from there. Or, if you also want to see Bayeux and the DDAY beaches, train from Paris to Caen, pick up the rental there, and drive to Bayeux. Use that as a base to day trip around the area, including MSM. After a couple of days, drive to the Loire Valley. Decide in advance which chateaux you want to see, since they are quite spread out. This will help you decide whether you'll base out of one or two different towns while you are there. We spent 3 days (4nights) in Amboise, and found we could manage 2 chateaux per day without having to rush ourselves.

To return to Paris, (the day before you fly home, I assume) drop the car at the train station in Tours (St Pierre des Corps) and take the train.

Driving in Loire area is pleasant, but be sure you have change for the numerous tolls on the highway.

Did this exact trip 2 years ago. Flew into Paris, picked up a car and drove to Monet’s home for a night.....gorgeous gardens. Drove through Rouen, Etratet, on to Honfleur for the night.....beautiful port city. On to Normandy and the DDay beaches for 3 nights. We love WW2 history so this was great...stayed at Bayeux. We drove to MSMichel to stay for a night on the island- a bucket list item that was well worth it. We left there and drove to Amboise and used it as a base to see Villandry, Chambord. Chenenceau, Aazy Le Rideau and others. We loved having a car and driving to these castles from Amboise-easy drives and beautiful countryside to see. Amboise was wonderful to drive back home to each night-Manior Les Minimes is the place to stay. Drove back to Paris and turned our car in and flew home.
Hope this helps. We have been to France now twice and think this trip was one we will never forget-so relaxed and fun. In a car you have the pleasure of driving through some of THE MOST BEAUTIFUL VILLAGES IN FRANCE- a designation given to small communities in the countryside. We drove through as many as possible-Gerberoy was outstanding- and had a pastry and coffee on our way to our destinations. What a treat!

Take a look ar the tour Paris and the heart of France for suggestions. Amboise was super.

Thank you all for your guidance and suggestions. Based on them we decided to travel from Paris to Tours and pick up a car (although right now it is looking like it would be less expensive to rent the car in Paris so we are flexible on that) we booked 2 nights in Amboise at Les Manoir les Minimes and then three nights in Azay Le R at Biencourt which helped to recuperate the budget. During those days we will visit 2 or 3 Châteaux per day depending on size and location, or not if we get tired of looking at so much excess. Then a night at MSM. We still have an extra night and are trying to decide between visiting some of the places recommended along the coast or adding a night in Azay and just enjoying the countryside. Our last night will be spent close to CDG but we have not looked at hotels yet. I read in the RS France guide that passes for visiting several of the Châteaux are available at the TI’s but there was very little information. Any help with that is appreciated as are restaurant recommendations. We believe that food is an important part of exploring a culture and we are willing to try places all around the spectrum of price and styles. The only food that we will not eat while traveling is American food. Thank you again.

I picked up a car in Rouen, went first to Etretat then worked my way down the coast. If you're going straight to MSM, Rennes is probably the best place to start. Check Caen as an option too.

After MSM, I spent a while in Brittany before going to Loire. I went to Fontevraud Abbey first, then Chinon, then traded the car for a bike (to try something different). A car is a good idea for both MSM and Loire. I trained back to Paris from Amboise. The train goes back through Tours. If you're further up the Loire, I think the train goes straight from Orleans to Paris.

One disappointment, I wanted to see Chartres on the way back to Paris but it wasn't convenient by train (had to go into Paris and then back out). If I'd had the car, I could have driven to Chartres then trained to Paris.

We just got back from France and did MSM and the Loire Valley! We actually arrived in Paris, rented a car and immediately drove to Honfleur (1 night stay), then Saint-Aubin (2 nights, saw some D-Day sites), then Mont St. Michel (1 night, I recommend packing just enough in a backpack for a night), then our homebase for the Loire Valley was Amboise (4 nights). We saw Cheverny, Chambord, Chenonceau, Chinon, and the Amboise castle. We encountered poor weather (freezing and rainy most days) but still saw crowds at the chateaus. Still had a great time and this was dragging along a 2.5 and 5 year old! Our favorite was Cheverny, it felt more personal and intimate and the kids loved the feeding of the hounds (usually at 11:30a, but get to the kennel 15 min prior to get a good viewing spot). We picnicked a lot and that saved money! After Amboise we drove back up to Paris, dropped our car, and spent our remaining 5 days of vacation in the city and using the Metro/bus.

Have fun! :-)

I don't know your dates, but if you have a week to juggle various destinations, I recommend looking at the tide charts for MSM, and pick a day for that location when they are the most dramatic.
https://www.ot-montsaintmichel.com/en/horaire-marees/mont-saint-michel.htm