France Itinerary for late August/Sept

Your trip sounds great! My husband and I made a similar tour 2 years ago, and if I can offer only one word of advice, it is this:
Do NOT stay overnight on Mont St. Michel!
The prices are tremendous, and what you are promised about your accommodations (beds, views, welcome baskets, etc) simply will not materialize. Parking is very far from any of the hotels, which are all up-hill on long and winding cobbled/bricked paths (not exactly luggage-rolling surfaces!); once inside the hotel, it's more and more stairs up very narrow flights and hallways, twisting and turning to find your room.
Once we were in our room, we left immediately to shoot some photos before we lost the light, and have some dinner. All the restaurants were closed (at 8:30!) except one, which was remaining open for a late tour bus group.
It was the most disappointing part of our entire trip, and the most important thing I learned was to pack a small, easier-to-manage bag for overnight or one-night layovers.
Meanwhile, the hotels on the mainland (half a mile up the causeway) are half the price, easier to access, and more faithful with their amenities & promises (I've been told).
So, stay on the mainland (and eat there, or pick up some picnic supplies in the store right on the main street), visit the Mont all day (see everything!), tour the cathedral (rent the audioguide!) and even stay or return late into the evening, but avoid sleeping on the mont!
Oh, and one other thing: If you travel by train (which we did, from Rome to Nice), overnight, make sure your cabin door is locked, and everything in your cabin is tied down! We were robbed (while we slept) and spent the first 3 hours of our day in Nice tracking down the police dept and the US consul to file reports and get info on replacing our missing passports, then on the phone canceling credit cards. What a mess!
Have fun, and stay safe!

Your trip is very similar to one my husband I just took in June. Hope you have a wonderful time. I agree with the post above about Mont St Michel. We paid in advance for our room, only to find it was not available due to burst pipes. They found us another room on the island, but we had to walk up innumerable flight of stairs to reach the hotel and then our room was on the top floor of the hotel, we opened the room door and there was one more flight of stairs! In recompense we were offered two free glasses of champagne and three boxes of cookies!
Instead of a train we rented a car and found it much easier for getting around the Loire valley. We had a GPS and a good map.Bon Voyage

I'm going to completely contradict another poster- STAY ON MONT ST. MICHEL for the night. Once the day-trippers leave and things quiet down, it's one of the most etheraly beautiful places on earth. You can tour the abbey first thing in the morning before the buses vomit hordes of tourists onto the narrow street. If you stay in one of the hotels on the island, you have access to a parking lot much closer than the general parking area. Most of the restaurants feature the same lack-luster menu, save one: Restaurant St. Michel. Excellent Normand seafood dishes here, and one of the best mid-priced restaurants I've experienced in France.

What Tom said. Mont St Michel is one of those places where sleeping there is way better than day-tripping. Not for the ambience of the room, but rather for the unique ambience of walking around the Mont after the day-trippers have left for the day and before they show up again in the morning.

You can easily fly into Amsterdam, in which case you might consider an overnight stop in Brugges on your way to Paris. (Italy is certainly possible, but not as logistically compelling.)

I loved Mont St. Michel, but caution against only visiting during the day. I would not visit it as a day trip from Paris, or from the Loire to Paris. MSM by day does not justify all that travel to get to it and back.

Our experience of staying on the island was great (though you do pay for it). Another option is to stay in Pontorson, where there are more lodging choices. I've never done this, but one compelling argument is that from Pontorson you get to see the Mont.

You could drive from the Loire to MSM, spend the night, and then return the car in Caen and take the train to Paris. But Normandy is a great part of France, and it's not all about the D-Day beaches either. Maybe spend a night in Bayeux or Honfleur.

If you want to do all these things you might try Amsterdam > Brugges (maybe) > Loire (via Paris) > MSM > Paris > Nice, flying home from Nice. Or Amsterdam > Brugges > MSM (via Lille, where you pick up a car) > Loire > Paris > Nice.

Other option: Skip Brugges and something else, maybe MSM, and spend a few days in Provence enroute.

Have a blast!

I would skip MSM and add more days to Provence. You'll want a car in Provence too but can take the train from Paris and get the car in Avignon.

Thank you for all of the suggestions. I see that staying on MSM is a heavily disputed topic. I think we'd like to try to stay on the Mont if we can - specific recommendations for accommodations would be great.

Right now we're looking at flying into Amsterdam (1 night), then Loire Valley (3 nights?), MSM (1 night), Paris (6 nights), Somewhere in Provence TBD (1-2 nights), Nice for the rest of the trip, fly out of Nice.

Does the length of our stays seem reasonable?

Traveling by train for all destinations, but probably renting car for the Loire and MSM portions.

Amsterdam (1 night), then Loire Valley (3 nights?), MSM (1 night), Paris (6 nights), Somewhere in Provence TBD (1-2 nights), Nice for the rest of the trip, fly out of Nice.

This is feasible, but I suspect Amsterdam will be a blur. Plan as well as you can to get the most out of your time there.

With only 1-2 nights in Provence, there is plenty to see in the cities of Arles, Avignon, and Nimes, all connected by rail. I wouldn't say no to a car, but you really only need one if you want to visit sights away from those towns.

This is a pretty nice taste of France, and the fact that you know what you want to see means you're going to have a great time.

We did a similar trip to France 2 years ago in September but in reverse order -- 3 nights Nice, 3 nights Arles, 2 nights Amboise, 8 nights Paris. Regarding MSM, we ended up doing it as a day trip from Paris as we were only traveling by train. We found that if we stayed overnight in MSM, then it would take a good portion of another day to get from MSM to the Loire by train. Initially, we were really worried that we were short changing ourselves with just a day trip to MSM but in the end our itinerary worked out great. The train/bus transportation between Paris and MSM was very easy. We were on the island for about 5 hours which was plenty of time for us to see what we wanted to see. So, in the end, if you can only work in MSM as a day trip, we would say that it is definitely worth it.