Renting car from Versailles or other Paris outskirts

The operating hours of the location where you plan to pick up and/or drop off a car could affect when and where you'd want to do that, especially if you had sightseeing plans that same day. Versailles could work, especially if you wanted or needed to get your car at a particular time of day, but you'd have some driving to do before reaching Caen, Bayeux, and D-Day beach locations. Some on this forum have suggested taking a train to Caen and picking up a car there. We dropped off a car in Caen after driving around Brittany and Normandy (picked it up in Lille after visiting Belgium). Your timing might or might not find Caen to be a better location for pick-up, but you'd need to get yourselves from Versailles to Caen (probably passing thru Paris on the way). If you're returning to Paris afterwards, you could arrive there by train again, after dropping off the car in Caen, if that made time and economic sense.

We rented a car from Avis (at least I think that's the company) on Ave Charles du Gaulle in the Neuilly Sur Seine in the outskirts of Paris. We took the metro there and the station is just across the street. From there we did have to make a u-turn a couple of blocks down the street but then it was straight to the highway. Since it's on the outskirts of the city and near the highway it might save you some time and stress when leaving Paris. Be aware that regardless of where you are returning your car in Paris the traffic will be worse getting into the city and it could take quite a bit longer to return so you should factor that in to return your rental on time. I believe they're open 7 days a week but don't know if the RER is near there.

My go to place for picking up cars on the western side of Paris is La Defense. It's a ride on the Metro Line 1 and then a five minute walk to EuropCar.