Mont Saint Michel Advice

Are wanting to lodge on the mountain or around there?
You might have limited choices this late in planning. Also the French rail society announced some train strike dates in May

http://www.bienvenueaumontsaintmichel.com/en/preparing-your-visit/arriving-by-car

There are parking lots across the bridge (not on the island) where you would leave your car and then take a shuttle bus onto the island. Train is so easy and pleasant, and then easy to rent a car in Caen, but perhaps you prefer the freedom of seeing things along the way. I don't have any lodging recs, as I didn't stay there

Parking is easy at the Mont. We stayed on shore for a view at night of the Mont but if we had it to do over we would stay on the Mont. Doubt there are rooms though this late.

We took a side trip from Paris to Mont St. Michel in 2013, and it worked out well. We took a train from Paris to Rennes, and then a bus to Mont St. Michel. The bus stop was right next to the tram that goes directly to the Mont. The connection times were great, perhaps 30 minutes or so. We stayed on the Mont at Le Mouton Blanc Hotel, which was nicely located on the main walkway to the abbey. It is really special to stay on the Mont overnight, because all the crowds of tourists leave in the afternoon, and the few guests on the island have the place to themselves. It is spectacular after dark. Have a good trip.

If you're so inclined: I stayed at a hostel in Cancale, about 30 minutes from MSM. The place was neat, a view of the sea, but it was like going back to the early 70's. The architectural style would have been new then and the people who run the place are hippies. I enjoyed it.

There are massive, computerized parking lots, operated by a contract infrastructure company. At worst, you might have to walk a long way to the electric shuttles to the island, but they also run diesel busses from the outer parking spaces. We enjoyed the walk, with a view of the Mont, and lots of hotels and shopping places on the mainland. Save horn honking, and pay for your space at a walk-up terminal just before you drive away. (See next paragraph, last sentences.)

As others have suggested, the main issue is whether you have a desire to sleep on the Mont or not. We didn't. And the general area has so much to see (especially in May, because of public gardens, which we like) that you might decide to get a car and do much more the just MSM. We've been to so many medieval towns, we didn't value an expensive night in a cramped room. Some people REALLY want to see the tide come in, or walk on the mudflats while the tide is out. (BTW, if you stay on the island, or in the more modern chain places on the mainland, you can expect a "deal" for the parking. Check into that.

Even if you only use Rick's book, there are wonderful places to see nearby: St. Malo, Dinard, Dinan, Dol de Bretagne. And you could see Coutances or Vitre on the way from the train, if you choose to. I don't know about the "Cider Trail" in May.

To the nice places listed by Tim, I would add Fougeres and Vitre. But now you'll need a lot more than two days!