If you can afford it, I highly recommend getting a personal guide for the D-Day beaches. There is so much to see, and they can tailor the tour to your interests. Look on TripAdvisor for reviews.
I also recommend staying in Bayeaux. It was one of the few villages that wasn't completely obliterated during the war, and is very charming. The tapestry is amazing. You can do a day trip to Mont St. Michel from there. We stayed at the Churchill, which isn't fancy, but is quaint, and just a block or two from the tapestry museum, and is the departure point for most tours.
If you want to stay in the countryside, Relais & Chateaux has some nice properties:
https://www.relaischateaux.com/us/destinations/europe/france