Carnac?

I find this sort of thing utterly fascinating and have personally seen so many chateaux that it would be a no brainer for me. My husband sees Carnac is 'just more rocks'. Here was our visit a few years ago.
https://janettravels.wordpress.com/2020/11/29/yes-ed-more-rocks-the-neolithic-alignments-at-carnac/
I have loved visiting chateaux but find them pretty much all the same especially inside -- my husband sees neolithic rock alignments as just more rocks in a row.

We did really appreciate our Carnac guide as he was fun to tour with, knew a lot and handled logistics of getting us back to our train. If you have a car, you can easily do all this on your own. Just do a little research to identify places off the beaten track.

You might be able to combine Carnac with the western end of the Loire region. Check out Saumur. Depending when you'll be there, you might be able to see one of the Cadre Noir horse shows, or visit the stables. There is also Fontevraud Abbey.

Carnac and neighboring Quiberon peninsula do not have the same landscape as the Dinan area either, so do not worry about repetition. I vote for Carnac.

My concern about the repetition of a landscape is due to the fact that we live in a coastal town. We are surrounded by beaches and saltwater 365 days a year but I appreciate the comments and opinions so keep 'em coming!!

I guess it depends on what coastal town you live in. I lived in Florida for 30+ years and found the area around Carnac/Vannes/Breton peninsula to be vastly different landscape.

I vote for Carnac as well. Do check on timing to enter the alignment area. I think it’s less interesting to view from beyond the fence and they were controlling access when I went pre-pandemic.

Include some of the other pre-history sites around Locmariaquer.

My reaction to the chateaux was similar to Janet’s. You know your kiddo better than we do but none of my then 13-year-old nephews would have been the least interested in château visits but could have gotten behind odd prehistory stuff. If you do choose Amboise, do Clos Luce to see the reconstructions of some of DaVinci’s ideas.

Good point! We are living on Puget Sound.

To me Brittany, including the Carnac area, in no way resembles Puget Sound area. I’ve mostly spent time in the Edmonds area.

I have not been to Carnac. But do you know that there are lots of stone monuments in Brittany, including a few much closer to Dinan. For example, there is a nice single one in Dol de Bretagne. It is not in an isolated, mysterious location. https://en.wikipedia.org/wiki/Menhir_de_Champ-Dolent

We were there in May before COVID and access to the stones was controlled. I think that some government managed tours of the sites allowed people to walk among the stones, but we saw none of that and we had to view from roads/ paths. As in the snapshots I posted, yu can enter some tumulos and there are some sites on farms etc where access is allowed. But the km rows of stones are fenced off. I suspect part of that is concern that some idiot will let their kids climb on them and be crushed to death.

Has anybody visited the standing alignments in Carnac, in southern Brittany?

No. Nobody has ever visited those.

Seriously, they're an interesting prehistoric feature and quite different from various châteux further east. It all depends on what you find more interesting. Which period of history you find more compelling.

And I'm not sure what other commenters are saying, but when I was there in the weeks before the first COVID lockdown in France in March 2020, it was wide open to walk among the alignments of stones, touch them, view them from various angles, and move on.

There was no controlled access. There was no limitation to view them only from roads or paths.

Interesting -- in May a year earlier access was restricted. I think it may be that starting in late May and running through summer tourist season that things are less open than March which is decidedly off season for that area. Brittany is cold and rainy pretty much any time, but particularly in winter. WE have encountered before, less restrictive access to archeological sites during off seasons. WE saw maybe 20 other tourists the day we were there at all the sites we visited -- and none at all in the more secluded sites like the tumulus on a farm. I imagine in summer there are busloads of tourists trampling through the place.

Just a theory.

Parts were fenced when we were there in May 2018. One field had archaeological excavation, another was a muddy mess after rain all the previous day, another had the sheep.

When I visited in April several years ago, the Archeologist leading our group and our guide both said that then the controlled access started in April. In fact our guide had to hang back to make sure the gate was closed and locked as others sometimes tried to attach themselves to the tour. At that time there was also a once a day guided tour in English from the visitor center. We were told the access was limited as too many people were wearing down the paths between the stones so they were in danger of being damaged.