During our trip to Paris in May, we plan to make also some day trips out of Paris.
In total we shall be in Paris for 16 days, so for 2 weeks we can use Carte orange for 2 zones, or maybe we shall buy carnets of 10 tickets. We shall take a taxi from / to airport.
My questions is if for some of the following destinations outside of Paris can we do use carte Orange, or we have to buy separate tickets.

From the list below, I think that for sure we have to buy train tickets for Reims. What about all other destinations, is Carte Orange useful?

St Denis
Chantilly
Vincennes
Malmaison
St Germain en Laye
Rambouillet
Vaux-le-vicomte
Barbizon
Bois Boulogne
Reims

YOu can take the metro to St Denis -- in fact, I think it is preferable as it's a more central stop than the RER (St Denis Basilique). St-Germain-en-Laye is in zone 4, Rueil-Malmaison is in zone 3, Vincennes is in zone 2, but you can take the metro there, also. You take a bus to Bois de Boulogne from Porte Maillot, which is on the metro line.

I haven't been to Chantilly in a long time, so am not up on that route. Used to be you had to take a regular SNCF train. There is no train stop (SNCF or RER) at Vaux-le-Vicomte, but if you intend to take the RER to the end of the line, I think that is zone 6, so you wouldn't want to buy a six zone CO just for that. Haven't been to Rambouillet or Barbizon. Reims is another city, of course, much too far away to be covered by Parisian transportation.

St Denis zone 2
Chantilly out of the zones
Vincennes zone 2
Malmaison zone 3
St Germain en Laye zone 4
Rambouillet (not sure) - zone 5?
Vaux-le-vicomte zone 5,6,7?
Barbizon zone 6
Bois Boulogne zone 2
Reims out of the zones

To find the Zone of a particular station, call up the Plan de Quartier from www.ratp.info and then click on the icon in question.

St-Denis - 2-3
Ramboulliet - 6
Vaux-le-Vicomte - outside

Anything not on this map requires a ticket on National Rail (SNCF):

http://www.stif-idf.fr/IMG/pdf/carte...mblancgris.pdf

A closer look at Paris and the immediate area is here:

http://www.ratp.info/orienter/f_plan...eur&fm=pdf

Thank you to all for the useful info.
Robespierre, thanks to the links that you gave me, I have now detailed prices for all type of Carte Orange and for all the tickets I need.

Thanks again.

Good question with lots of helpful answers. Lucky you, valtor, to be able to be in Paris for two weeks, have a wonderful stay. Deborah