I'm posting late here, Tom, but I'll throw in my two cents. The approach to Mont St. Michel is fascinating; as you drive toward it, you can imagine how it becomes an island at high tide. The walk from the bus parking area to the entry is a fairly long jaunt. Then when you get inside the walls, you come to a narrow pedestrian street that is lined on both sides with tourist shops, and when we were there in May 2001 every space was filled with people. However, if you look beyond the crowds, you can imagine the pilgrims making their way up the picturesque street. The walking street winds up at a fairly steep incline, then as I recall quite a number of steps lead up to the church itself. I have walking difficulties, so at this point I waited for our tour group while they went inside and toured. Lots and lots of steps inside, I was told, and others here seem to bear that out. However, even with missing the "main event", it was a fascinating stop, and you can wander around outside the church through alleyways with pretty views from various vantage points.
I loved the town of St. Malo. JoAnn, if you plan to wander around there, you should have a great time. The walled town was damaged heavily in WWII but has been rebuilt masterfully, and unless you knew it was post-1945 construction I don't think you could tell. The cobblestone streets were picturesque, the shops very nice, the views from the top of the city walls pretty. Really a fun location. I would go back in a heartbeat. Claudia has posted some good information that gives you the flavor of the town. Enjoy!