Route planning assistance

Your plan looks pretty good.
Arles - if you sleep in the historic center, get a hotel that will facilitate your parking.
Nimes, Arles, Avignon are best reached by train (leave the car parked in Arles on those days).

If you haven't booked your plane tickets yet, you might consider flying home from the south of France. I've flown in and out of Montpellier, or Nice is another option. You would probably have to change planes at CDG. Personally, for the amount of time you have -- 12 days excluding flying days -- I think it would be better to take the train from Normandy to Provence. It isn't that much of a hassle to drop the car, take the train, and pick up another car. If you book through AutoEurope, you will probably get placed with EuropeCar, which has offices at most train stations. The only problem might be getting an automatic, if that is what you require. I've never had a problem getting one at CDG or Montpellier, but it could be a problem in a smaller town like Arles. Be sure to get some good regional maps - don't rely solely on GPS - and don't be afraid of the D & N routes. They are slower than the Autoroute, but more scenic and you're not likely to get a lot of traffic except when going through towns. The autoroute is my choice for a long haul, but I like the D & N routes for sightseeing.

Following on Carol's reply, the closest airport to Arles is Marseille, which is a major one with flights to many European destinations; in other words, you don't have to connect through Paris, but can also go through Amsterdam, Frankfurt, etc. Since you haven't booked your flights yet, you should definitely see how much "multi city" flights into Paris and out of Marseille, or vice versa, would cost. Don't look at two one-ways, as that's often much more expensive; use the "multi city" option on Kayak, Air France, etc. And remember that even if the flights are more expensive, you save time and money by not backtracking.

Actually since you are going via the Loire valley , your drive would be from Amboise to Arles and most of that can be done on the Autoroute but it would still be a long day. If you take the E11/A75 it is mostly toll free and you could break the trip at or near Millau and have a chance to see the Viaduct du Millau, one of the most spectacular bridges in the world. Then on the way to Arles you could stop and see the Pont du Gard which was the state of the art for bridges in 50 AD ... there has been a big change in the state of the art.

Two nights in the Loire Valley is fine. If you have to cut Normandy to 3 nights to get 2 in Loire, then I would do it.

If you are flying trans-Atlantic, consider choosing Marseille as your arrival point. You will probably have to change planes in Paris or another gateway. Then work your way to Paris and fly home from there. I've used this strategy because flights starting in Marseille usually depart very early in the morning to allow for the connection to the trans-Atlantic flight in the gateway airport. Leaving from Paris can put you on the trans-Atlantic flight without a connection, and with a more civilized time of departure.

Thanks for help. You have given me some different ideas/perspectives....my exact reason for posting. Thanks again.