glenn1000, I haven't found my journal from this trip - assuming I kept one! - but found a folder of keepsakes and brochures, postcards etc, so can share some of the highlights, if not actual itinerary:
Mont St Michel, of course.
We spent a couple of delightful days in Dinan, including a walk along the river to the medieval town of Lehon.
By the way - Dinan is apparently "mentioned in the Bayeux Tapestry as the place where William and Harold defeated Duke Conan of Brittany." (I just read this in my travel print-outs!)
From Dinan we drove many of the coastal roads to the north - the Emerald Coast - and got out and walked around the scenic rocky peninsulas. Went to a reserve / bird museum on a little island you can drive to. We hoped to see puffins as we had on an island in Wales, but didn't, except on their postcards.
Ploumanac'h as I said above - walk the paths thru a clifftop rocky area, old lighthouse etc. One of the most beautiful places I've ever seen. Pink Granite Coast. This is where signs started being displayed in 2 languages, French and the Celtic-related Breton language.
Various prehistory sites: Carnac is a huge one, hundreds of 6000 year old megaliths and a museum, near Vannes, and one of our longest daytrips from Dinan. We saw just a few glimpses of Gulf of Morbihan before it was time to drive back to Dinan. Locmariaquer is another prehistory site we went to near Carnac - and others we just encountered while driving thru the countryside and seeing signs with the icons for dolmens and menhirs - ancient stones. We loved discovering these, sometimes traipsing thru the woods to find them.
Gorgeous ruined castle at Fougeres (I don't care for castle tours with lots of tourists - we like to be the only tourists we see! and so we were at Fougeres). We spent our last hour there before flying out of Rennes when leaving Brittany and France, perfect last stop.
Brittany was way too big to see it all by daytrips from Dinan, you'll see more if you hit the road - but since timesharing, we prefer the daytrip model.
If I recall other places I'll let you know, since I'm sure I'm leaving things out.
A book set in medieval Brittany that I really enjoyed and recommend: Holy Fools by Joanne Harris.