Reasonable itinerary for 4 nights outside Paris?

On Tuesday night, I would stay in Amboise again and save the whole drive up to msm for weds. You don't have time to see châteaux AND drive on Tuesday.

I don't like to be that far from the airport the night before a high stakes flight. If you have car trouble or the highways are parking lots, you miss the plane. I'd drive to CDG and turn in the car the evening before the flight and stay at the airport that night. You can get dinner in Normandy before the drive to CDG or else arrive earlier in the day and take the train into Paris for dinner.

I agree with Janettravels44. There are hotels right at CDG, which fit all budgets and position you well for your flight. There are Novotel, Ibis (both Accor hotels), a Hilton and Sheraton. A short walk from either hotel will bring you to the free underground shuttle train connecting the terminals.

Looks like a great four days, but .... Janet is right, you're cutting it too close the final morning. You want to be at CDG at least three hours before the flight, so by 10 AM, and there's a lot of morning traffic to deal with.

I agree with sanderskin about the chateaux, spend Tuesday night in Amboise. From there to MSM is about four hours, giving you time to see the Mont and spend the night either on it or on the land end of the causeway (perhaps better for early morning start). Thursday morning to the beaches (two hours to Caen, beaches nearby), but instead of LeHavre stay inland and spend the night much closer to the airport, or maybe at the airport or nearby town of Roissy.

Or.... choose between the Loire and Normandy/MSM for your four days, and assume that you'll return for what you missed. You may enjoy exploring one area more fully without having to race around against the clock.

Is one full day enough to see the highlights of the Normandy beach area? My husband and 13 year old are keen to visit the American cemetery and a few other things in that region. Could we drive early Thursday morning from MSM to D-Day beaches, spend the day, then leave late in the day for a hotel closer to the airport?

We spent about half a day driving from Bayeux to Arromanches, to Omaha Beach and the cemetery there, and back to Bayeux, which is quite close by. The next day we spent most of the day driving from Bayeux to Honfleur, looking at the harbor and church with a coffee stop, and on to CDG with lunch somewhere enroute. From MSM you'd spend maybe two hours getting to Bayeux or Arromanches, giving you time to explore more than we did. (One thing we wanted to see but didn't find was the German cemetery.) And time to get some distance toward CDG, or maybe all the way there if you drive into the evening (and why not?).

What you'd miss in Normandy, that I wouldn't want to miss, is Bayeux with its Norman cathedral, world-renowned tapestry (the Normandy invasion in reverse 900 years before), and WWII museum (and/or the museum in nearby Caen). And Honfleur with its lovely harbor and overnturned-ship-shape church. Like I said above, I think you're trying to fit too much into your four days. You could do justice to Normandy without the Loire, or vice versa. But we like to move a little slower, so chacun a son gout!