Easiest place to drop a car rental in or near Paris?

Try dropping off at the Gare du nord... We picked up there last June and it wasn't too bad. It's on the north east side of the city so would be convenient to coming back from Reims.

If in Beaune, I'd consider Dijon station and taking a TGV to Paris in 1 hour 35 minutes.
If in Reims, I'd consider Reims station and taking a TGV to Paris in 50 minutes.
Europecar and Avis have rental car locations at these stations. From Dijon you arrive at Gare de Lyon, from Reims at Gare de L'Est.

Wherever you pick, make sure you get detailed information on the exact location and driving instructions to get there. We turned a car in at Gare de l'Est only after circling the station several times looking for signs to Hertz -- high stress!! (Finally gave up, parked in a garage and walked into the station to find Hertz -- sign was about 12", tucked down a driveway. Yes, we could find it NOW and might consider using that drop-off point on another trip ... but Orly would look good too.)

I had just been in the same position in Oct. I was looking for a convenient place to drop off in Paris after a drive up from Gray which is near Dijon. We ended up dropping the car off in Dijon at the train station, our iPhone's gps got us there no problem. We took the high speed train from Dijon to Paris, it took less than an hour and a half at speeds up to 302kmh:) We didn't pre buy our train tickets so we paid a lot and there was only 1 train with 3 available seats(this was a Sunday afternoon) but I feel it was worth not having to make the long drive and the added stress of finding the drop off spot in Paris. If you go that route and have a definite plan, buy the train tickets ahead of time. Dijon was pretty easy to navigate.
I think we would have tried Orly as a drop off if we had decided to make the drive.

Another option would be Marne La Vallee train station (aka Disneyland). Hertz and Avis both have locations there. You could ride the RER A into Paris. Change to the No 2 Metro at Nation will take you up by Montmartre.

Excellent suggestions from everyone! Thank you very much! Laura B, I had a almost identical situation happen a few years back when trying to return a car in Munich and I want to avoid that stress again. :) And Sam, thanks for all the great info, knowing what car rental companies operate out of which stations really helpful.

Laura B- we had the same problem in Lille. Barely made it before they closed at 6 (and that was after I ran into the train station to ask the guy at Europecar where to park). Having said that, we returned a car at Orly in 2012 and it was very easy. It is very well signed and easy to find. I looked into a lot of "ideas" and decided I want to get as close to Paris (without hitting the city traffic) as I could to avoid a train fare (I am already paying for the car for that day...I did not want to add on train fares). While there was a cost to get from the airport to where our hotel was, it was very reasonable. This last September, we picked up our car in Versailles to avoid the "airport charge" for picking up a car at an airport (no charge for dropping one off at an airport). It worked great, but the place closed at 6:00 so we had to be sure we could arrive in time to get our car before closing. We also had to walk a few blocks from the train station to the car rental. Orly stays open a lot later since it is at an airport. Overall, I would always return my car at Orly.

BTW, I edited my last post to the No 2 Metro from Nation to Montmartre district.

We picked up our Europcar rental car in Reims. Have you checked on returning it there? It's a small operation, easy to find. The train ride into Paris is about 45 minutes. It's about a 10 minute walk from the rental office to the Gare de Reims in the center of town.

We had an experience similar to Laura B. at Gare du Nord. Ended up missing our train and it was VERY high stress!!! On another trip we returned a car in Dijon and had absolutely no trouble at all.

We picked up a car in Paris to drive north and I spent probably an hour mapping where all the car rental places were (we used AutoEurope and ended up with a rental from Europcar - they had more then a few locations to choose from.) We needed somewhere we could walk to from the Metro, that was open on a Sunday and not right in the historic center. I finally decided on the location at Ave Foch, which was right past the Arc Triomphe, but easy to get to the ring road out of the city....and we could easily walk there from the metro with our luggage. We actually went over the evening before so we could find it (it is in an underground parking lot, so it took us 5 min to figure that out).

And all would have worked out, except we had a GPS mishap and ended up...in the city centre...lol. Our saving grace - it was mid-morning on a Sunday, so not much traffic! We actually easily got heading the right way, then got turned around because the GPS was speaking German and we ended up programming the last place the person before us went to before figuring out how to switch the language (it was an integrated GPS unit). We were pretty much GPS virgins, having only used one before to drive to Maine, so we were a bit clueless...well, it was good for a laugh!