One Month Sabbatical with Toddler

Go with the Dordogne specifically the Perigord Noir region; stay in Montignac Periguex or Sarlat-la-Canéda (more British tourists but they have a serious market on Saturday).

The Dordogne is uniquely picturesque in my experience, almost like a fairy-tale land (Ive traveled through much of France but not Brittany). We were there with kids, although not as young as yours, and they also found it magical, between the castles with trebuche, the caves with caveman paintings, the river for swimming and canoeing (and a tree swing), walking Sarlat (where Ever After - the Cinderella re-make was filmed), and just driving through stunning beauty. The food is amazing, with many markets. But the area also feels lived in. There is a large grocery store, and many people doing workaday things.

Of course a village in Provence would be great too, with more to see in the surrounding area. The Dordogne is removed from other places by a greater distance. And it might be sunnier and warmer in Sept-Oct in Provence

Jessica

I'd consider Bourgogne, specifically Beaune. While Beaune is a bit touristy (I hear English on the street there far more often than anywhere else I regularly visit other than Paris), there are a lot of good restaurants, good parks for your daughter to play in, has a nice Saturday market, and is fairly close to several things that probably would interest you and your husband as well as any visitors you may have. It's also near A6 (from Paris to Lyon and on to Marseille, or A31 to the closer Dijon) so short trips to Dijon or Lyon (especially Lyon, which is much bigger and far more interesting than Beaune, but it is a city) would be an easy thing to do.

My wife and I did a 6-week trip to France a little more than a year before we moved here, and it was around the same time (mid September to the end of October). We had fabulous weather. Last year, though, the weather in the autumn was not so good -- it went from hot to wet and chilly pretty quickly. I hope you'll have weather more like we experienced on on our trip.

Enjoy yourself!

I would add that there is also a French way of city life, too. I'm not saying that you should be more interested in that than in provincial daily life. It depends on your interests. It has been noted in American newspapers that some lovely old places are starting to lose their ... "Frenchness".

https://community.ricksteves.com/travel-forum/france/as-france-s-towns-wither-ny-times

France is glorious. Put your finger randomly on a map of France and you'll probably be within a few miles of a charming place to stay. However, there are differences in weather (Brittany tends to be cool and overcast even in midsummer) and accessibility, especially if you may not have a car. (I note that you said only that you would "likely have a car".) Without a car I'd want to choose a place of some size that was a good hub for public transportation. Even with a car, spend some time on ViaMichelin.com before you commit to a rural area like the Dordogne, to be sure you won't be subjecting yourselves to longer-than-expected drives.

The other thing is that this seems to be your first trip to France. I'm always a bit doubtful when folks propose to spend all of a fairly long vacation pinned down in one location. It's an intriguing country with a great deal of variety. I would prefer a week or ten days in multiple locations. I do get the desire to settle in at one spot; it's just that I tend to settle in for a shorter period of time.