12 Days in France - Paris, Mont Saint-Michel, Loire Valley, Dordogne

DX, You are starting off well, but Day 4 will be taken up by a 4 1/2 hour drive, so after checking in at your Ambois lodgings you will effectively have time to visit only one chateau (I would choose Chenonceaux). On Day 6 your drive will probably take about 5 1/2 hours. You don't show any plans for touring or visiting anything that day, so that is good. I say that because in route planning with viamichelin.com (or other sites) they don't usually allow time for gas/food/comfort stops, so I always add another hour to my drive time. Also, the routes shown are usually on the Autoroutes. You may choose to take the slower and more scenic roads; if so, it will take a bit longer.

IMO Rocomadour is very disappointing because it is so touristy. There are lots more scenic towns in the area where you may prefer to stay. Do a little research on nearby towns. On Day 8, you show driving to Sarlat, visiting the town, going kayaking, visiting Chateau de Beynac and La Roque Gageac. That is too much for one day. There are not enough hours in the day for all those activities. Kayaking alone, including before and after prep and return to car, etc. use up about 4 hours. Visiting Beynac castle also will take about 2 hours. You need to factor in time to go from place to place and eat lunch. Did you mean these things are for 2 days? You do show 2 listings for Day 8.
I have a suggestion to throw in here. On your drive to Bordeaux day, you could visit one of the prehistoric caves in the morning and leave for Bordeaux about 1:00. It does seem a shame to be there and not see Lascaux IV, at least.
Bordeaux from Sarlat takes about 3-3 1/2 hours and you can drop the car at the train station. There are hotels around the station and lots of places to eat within walking distance, plus Bordeaux has a good tram system. The TGV to Paris is just over 2 hours, so if you leave on an early train you will have a good afternoon and evening in Paris. A realistic day trip to Versailles takes up most of a day, so other activities (after return from there to Paris) should probably be things that don't need 3 or 4 hours each, so you aren't rushed.
Overall, your plan is doable. Just be sure to factor in time to check in and out of your lodgings, gas stops, etc. on driving days and find time to sit and have a a relaxed meal. And check out what you have listed for day 8.
Bonne chance et boin voyage!

I confirm Judy's recommendation about the Dordogne.

Please, even if it's March, don't make the mistake of staying in Rocamadour, it's THE tourist trap!

Try to find a place in Martel instead, one of the most beautiful villages in France. At least you'll have restaurants, bars and real shops, not sellers of trinkets made in China for groups of tourists on organized tours.

https://maps.app.goo.gl/Cjc9ZP2KZn8Fe47s6

https://www.visit-dordogne-valley.co.uk/discover/cultural-heritage/villages-to-visit/martel

If you want to go to Rocamadour you can still go, it's less than 30 minutes drive from Martel.

In Martel you will be in the middle of an area with 5 other most beautiful villages in France within a 30 minute drive.
You have already planned Carennac and Autoire, the others are:
Turenne, Collonge la Rouge, Aussoire and Curemonte.

There are several hotels and B&Bs in Martel, check for example if there are still rooms available at the 5* B&B "La Devinie".

https://www.la-devinie.com/home.html

There is also nearby the Gouffre de Padirac but it only opens from late March, like many other caves with or without painting

I made this map, locate Martel and see the activities and visits you can do. 3 full days does not leave you much time, you will only have a small overview of the region

https://www.google.com/maps/d/edit?mid=1OdPOg8AgsNn0Jlv1cNHkujaWv9p_Jpc&usp=sharing

About kayaking, there are quite a few kayaking agencies closed until April and this activity is very dependent on the weather, water level and flow of the rivers.

I'll third the disdain for Rocamadour, especially for an overnight stay. We spent 10 days in the Dordogne this Fall and if we had a do-over we would have skipped Rocamadour entirely.

We loved Beynac and it's castle and I highly recommend one of the caves; either Lascaux or Font de Gaume.

On your way to Bordeaux consider a side trip to Saint Emilion.

One tip about driving in the Dordogne is to not rely on your GPS. Instead follow the white signs when going from town to town.

I would suggest flipping your chateaus on days 4 and 5. Drive straight to Amboise, drop your luggage at your hotel, and depending on where you are staying, walk to Chateau d’Amboise and Clos Luce. That would leave you a full day for the bigger chateaus. And you could possibly add a third - Cheverny or Chaumont-sur-Loire. Or just have more time to spend at Chambord and Chaninceau.

In summer 2021 we visited Loire (staying in Amboise), and then drove to Dordogne. Our trip report might be useful reference (Parts 2, 3, 4): https://community.ricksteves.com/travel-forum/trip-reports/trip-report-france-28-days-aug-sep-loire-dordogne-languedoc-roussillon-lyon-burgundy-honfleur