Mont-St-Michel to Brest

this isn't exactly what you asked, but can you reverse this? Visiting Mt St Michel thru the early afternoon puts you there when it is most crowded. And you miss the beautiful sight of seeing it lit up at night. On the flip side, the attraction of Dinan is walking around the town, the town walls, and down to the river, as well as perusing the shops. At night not much to do but have dinner somewhere.

I would flip the order and visit Dinan during the day, then drive to Mt St Michel around 3pm or so and stay the night at one of the hotels across the bridge. A little more driving the next day to Brest, but worth it IMHO.

If you want to sightsee along the way from Dinan to Brest prepare to use the whole day. I found last June Fort la Latte stunning on top of a cliff west of Dinard, but needs a serious detour. This was the most western point of my visit to Brittany, so can not help you further with ideas about driving to Brest. But maybe places closer to Dinan can be nevertheless of interest for you during your stay there.

Exploring the area around Dinan I liked the coastal road between Cancale and Saint-Malo. Between St-Malo and Dinan Saint Suliac is a lovely former fishing village of Bassin de la Rance. Lovely tiny place just at the southside of Dinan is Léthon with the castle and the abbey. A really big menhir is Menhir du Champ-Dolent south of Dol-de-Bretagne. North of it Mont-Dol is a good place for a panoramic view overlooking the lowlands and the bay of Le Mont-Saint-Michel.

It would be a pity to arrive first in Dinan, then drive back to the east to Mont Saint Michel, and then again to the west to Brest. The crowds in Mont Saint Michel, the pleasure to see it at night, also depend on the season you are expecting to travel. When will you be in Brittany ?

Many places are interesting on your way from Dinan to Brest, you could spend a few days more in the area! Closer to Dinan, there are some additional medieval towns like Léhon, Jugon les Lacs, Moncontour (in addition to what was already suggested). Near Dol de Bretagne, the town of Combourg also has a beautiful castle. Fort La Latte /Cape Fréhel is also worth seeing along the coast. Halfway between Dinan and Brest, you can consider the pink granite coast with a small detour (beautiful towns too, and for example the St Uzec menhir, Tonquédec castle). Closer to Brest you could stop in Morlaix, Roscoff, without forgetting the numerous parish enclosures.

You can check some ideas for places to see on http://visite.bretagne.free.fr/index.php/en/itineraries.html

To all respondents: Merci for the suggestions. Alas, due to family considerations we must go to Mont St michel first and get to Brest the following day at least by mid-afternoon, if possible. Glad to get referrals regarding the menhirs and Dinan and routes, as I think they make a nice change from the castles, museums and churches we will see on our three week visit to France. Perhaps we may need to go further west than Dinan to stay the night after Mont St Michel, to shorten our drive the next day. We are spending 6 days in Paris, then 13 on the road...Normandy, Brittany, the Loire Valley, a dip into Burgundy, then 3-4 days in Alsace-Lorraine and Champagne. Only 1 or 2 days require more than 3-4 hours driving total. I'll use the great site Via Michelin to plot out the routes.

P.S. We will be in Brittany in early May.

I stayed in Cancale one night then spent one day seeing St. Malo and Ft. La Latte before staying in Dinan.

After Dinan, I drove through Treguier then to some small towns, each with a Parish Close worth seeing (St Thegonnec, Guimiliau, and Lampaul-Guimiliau).

That was as far west as I got before I turned south then back east on the southern side of the peninsula.

I thought Fort La Latte was worth going out of your way for. I liked Treguier but I'm not sure I'd recommend it as another good side trip. The small towns aren't far off the main road to Brest. The parish closes aren't big, just unique to this area - they can be seen fairly quickly.

If you go south afterwards, I really liked Locronan, Auray, Vannes and, of course, Carnac as good stops. I think they are a good representation of the area but there are lots of other good choices.