We are also planning our first trip to Normandy in October as well as our first time hiring a car in Europe, we are slightly worried as being from Australia, we aren't used to driving on that side of the road.
I have done an awful lot of research though and now have a few things locked down that might help you.
We have been to Paris many times so this time we are going straight to Rouen for three nights to get over the jet lag. We will then pick up a car, which is already reserved through Sixt. We did look at AutoEurope and other sites, but getting it directly was lots cheaper.
We're then driving to Etretat for two nights, then Honfleur for another two before getting to Bayeux.
I did a lot of research into staying in Bayeux or Caen, and pretty well all I read agreed with what is written on here, Bayeux is the place to be. Such a darned shame about the tapestry though, I've wanted to see it since I was a child, so now I will have to return ha ha.
We have booked a hotel for three nights in Bayeux with private parking, there were three or four to choose from, we have chosen Hotel Le Lion d'Or as we also like having a lift and a restaurant.
After our three nights, we then go to MSM for one night. We both really wanted to stay on the island, but after six months of reviews and discussions, we've changed our minds. The reviews are mostly very bad, and I don't want to climb a million stairs.
We've also been warned about leaving our larger suitcases in the car overnight, as theft from the cars parked there is apparently becoming an issue.
All up we've decided to stay at the Mercure on the La Caserne (I think that's what it is called), which has a restaurant specialising in the famous lamb, and gets far, far better reviews than anything on the island.
Our plan is to arrive late in the day, get settled and have a look at MSM, we will then come back for dinner and after dinner return to see the island without crowds. The next morning we will do the same, have a super early breakfast, make an abbey reservation for the earliest time, but just get over there and enjoy the peace, well that's the plan anyway.
After we finish, we will then head to Caen, drop our car at Sixt at the station and catch the train to Paris for the last couple of weeks of our journey.
Hope this is of some help to you.