We are picking up a rental car at CDG and touring around Normandy (staying near Bayeux) in mid May. After that, we are going to Paris for a few days. We aren't sure where to drop off our rental car, as we don't want to drive into Paris. We will probably take a train in from wherever we drop the car. We are staying in the 5th. Does anyone have any suggestions of somewhere on the outskirts of Paris, but near a train station? Or, if you have a different suggestion, that would be helpful too!

We dropped off ours at Gare Montparnasse. It wasn't too bad as we were entering the city from the South.

See if the ;rental agency has an office in Versailles. Chartres is another possibility.

Just drive into Paris or drive to Caen for example and take the train in from there. If you are going to drive all the way to the Paris burbs you can just as easily go into Paris if not actually easier.

Driving into Paris is super easy and certainly no more difficult than driving in the rest of France. And if you have any luggage, you will be punishing yourselves if you don't drive in.

Any of the train stations is a good drop off point as they are easy to find, unlike the car rental addresses in some of the suburbs.

I usually rent from Hertz and drop off in Paris. It's a fairly easy drive. Hertz has a location in the parking garage at the carousel du Louvre. So, all you have to do is follow the signs to teh Louvre. If you get lost everyone knows where you are going. The parking garage entrance is on Rue Rivoli right next to the Louvre - very easy to deal with and you can take a quick cab ride to your hotel.

We also dropped off our most recent rental at Gare Montparnasse. It's easy to spot with the tall landmark. The drop off point of most rentals here is actually the parking garage of Le Meridian hotel, just next to the hotel.

We did the opposite of what you are doing. We rented a car through AutoEurope. The rental agency was EuropeCar and the office we used was the 8 Ave Foch address (just a block or so off of the Arc de Triomphe.) It was a very easy straight shot from there out to the Periphique (ring road) expressway that loops around Paris. It was extremely easy on a weekday late morning and would only be a short taxi ride to the 5th arr.
Using this agency location will also put you on the side of Paris closest to Normandy. You have only a few minutes of driving within the Periphique after you get off the straight expressway from Normandy.