May as well rent in Paris like at La Defense - business city with lots of rentals I suppose and well out of Paris itself - take RER there and pick up car and head for Giverny and Rouen. Mantes-la-Jolie may be a city a bit farther out on Seine with such car rentals.

I would not rent at la Defense. Firstly, you have to get there. Secondly, the roads and connecting ramps around la Defense are some of the most confusing in France. Make a wrong turn traveling through la Defense and you do not correct it by going around the block. Thirdly, the toll on A14 from la Defense is more than double the toll on A13 from Porte d´Auteuil.

bornintheusa - I am not suggesting that you avoid a rental car; just the opposite. Rent one from an in-town office near Charonne métro. Finding an office just to the east of Place de la Nation would be ideal. Follow Cours de Vincennes to the périphérique, which is straight ahead the east. Enter onto the périphérique (a right turn), orbit clockwise to the south until you are near Porte d´Auteuil and look for the A13 exit. That´s all you need do until your destination in Normandy.

The preferable solution is often the simplest.

I think you should get the rental car for sure. I'm just not sure the added benefit of driving from Paris to Rouen (unless you are definitely stopping at Giverny) to tour Rouen and then head out. Getting in and around Rouen, especially the center city areas isnt worth the hassle of driving from Paris, IMO. Train up to Rouen from St. Lazare is 13 euro one way. I'd rent the car there, store my luggage in the car, then tour the city sites. Just down the hill from the train station is the Cathedral, and west of there is rue Gros Horloge, which leads to the Jean d'Arc memorial area. The museum is just east of the Cathedral. When you complete the Rouen tour, then go back to the car and head out to Honfleur or wherever.

Nice information here, thanks.

*dollars, not euro

Well getting to La Defense is simple via RER but the tangle sararastro describes sounds daunting. Paris traffic on weekends, especially Sundays, is much calmer than week days and if you can easily get on Peripherique then it should be fine though bottlenecks can always happen.

Thanks everyone for all of your advice and sage expertise--the car is rented out of Montmartre (north of Sacre Coeur) (the only one in the area that actually had a Sunday drop off manned office!!) ---the train to Rouen only takes about half an hour less time than driving as it makes tons of stops on the way---this drop off isn't too far from Gare du Nord which is where we leave out of Sunday afternoon for Brussels. Love how with all of your help my trip is coming together in bits and pieces!!

Getting into and out of Rouen...yes, that can be difficult. It once took us seven passes over and over the various bridges before we finally got onto the road leading to our hotel on the opposite side of the river. Good luck, bornintheusa!

Trains also take you back to Saint-Lazare station - about half hour by RER from Gare du Nord - so great location to return car.

Will you stop at Giverny en route to Rouen (Monet's House and Garden).

did you book Thalys tickets or if too early - www.thalys.com - can get as low as 29-39 euros if book far enough in advance vs about 100 euros or so at full fare.