Only 2 days in Normandy - D Day Beaches and Mont St. Michel

Well given that your 2 days isn't 2 days and is only a single day, and that you're "not a super history buff" and "Mont St Michel looks gorgeous", the best thing clearly is for you to skip Normandy and have a bit of fun in Brittany before you go south to the Loire Valley. If you try to rush you will enjoy neither. That's not what I would do, but you're not me.

The D-Day beach experience done well should take a whole day but could possibly be done in a half-day. Arriving at Mont St. Michel at about 5pm and staying until about noon the next day is ideal. Explore the island by yourself in the evening and then take a tour of the abbey in the morning. Do not miss the opportunity to sleep on the island! If you have time in Bayeux, visit the Bayeux tapestry and take a peek at the cathedral. Going to Bayeux first and then Mont St. Michel should position you for your Loire Valley travels.

To do the D-Day sites justice, you need two full days minimum, imo. If you just want to see one or two beaches, a half day will work.

The D-Day area is large, complex, and deeply involving. If you try to crash through it you will miss it. Some people only want to go to a beach and say, "done it - move on." IMO they don't do it justice. Why not save a pile of money, go down to Orlando, see the mouse, and go to a beach, and say "done it - move on." After all, aren't all beaches the same? But, that's only my opinion.

With a car, if you get to Bayeux by the time the museums open, you can catch both museums, the cemetery, and one beach, plus drive to MSM by sundown. But you have to do it in that order. It's a bum's rush and doesn't do it justice, but it does it. How you preposition yourself to Bayeux that early and the time it takes to get back to Paris from MSM the next day is another issue. To me it looks like an afternoon, a night, a day, another night, and a morning. I have no reason to think it could be done in that amount of time using public transportation.

We did both on that same timetable in reverse two years ago (Loire - MSM - Beaches) and it was just fine, but we had a car. I don't believe there is any rational way to see both in that time frame without a car unless you sign on to some tourist-filled charter bus that is both expensive and visits the sights when they are most crowded. MSM is great overnight and the beaches are simple by car. All you need is a good map and these days all you need for a good map is Google Maps and a printer.

One other option without a car ... The Hotel Churchill in Bayeaux runs a shuttle to Mont St Michel. Check their website. They leave in the morning so you would need to stay in Bayeux the night before. You get 3 hours at MSM which was enough for me. You get back to Bayeux by 3pm which gives you enough time to see the tapestry, cathedral, and walk around the town. One caution. Although the email from the Hotel Churchill may tell you that you are confirmed, this evidently doesn't mean much. The day I arrived, they told me they would not be able to run the shuttle for the day I booked because a couple had cancelled and they could not run it for one person. I was not happy, but when I returned in the evening to the hotel, another couple had signed up and they ran the shuttle for the 3 of us. By the way, I much preferred the WWII tour (I used battlebus which isn't around but some of the guides still do tours) to the visit to MSM. MSM was pretty. However, some of the stories that I learned on the Battlebus tour were things that I will remember forever.