Havung taken my son at your child's age here are a few things that we enjoyed. The RER train from CDG to Chantellet and then to the Arch dt, then a short walk downhill to the Marriott. Other things we could do together, The Aquarium, Seine cruise, ice cream in Latin Qtr. and best yet was the Big Red Double Decker Bus, (You will need to conserve the families energy or it could be rough on you). By the way there was a great park not far that is just for kids that was great, the concierge will know it.
Dining, is always great at Relias du Venice, if you like great, reasonably priced steak That is all they serve, it is right next to the RER station at Port Mailliot. I'll shoe some pictures. Be prepared for some cool weather, have a great trip!
It will probably still be cold in March, but the carousel in the Jardin du Luxembourg is great for kids that age, as are the pony rides. Not sure if they will be out at the time, but people float remote control boats in the Grand Basin at the park.
The Cite des Enfants is a good childrens museum for 3 year olds.
More Paris Links:
http://www.rewards-insiders.marriott.com/photoAlbums/1101 La Défense, Paris, France
SusanL (Renaissance Vendome)
Thanks & CDG to Renaissance Le Parc Trocadero (Renaissance Le Parc Trocadero)
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