The easiest but most expensive [under 50€] is a taxi parisien. The cheapest is the RER to Chatelet and then the Metro or city bus.

I don't rec. the taxi. CDG is far from the center of Paris. Take the RER and then go by metro. You can look at the metro maps and stops online and it should be easy. There is a metro stop right under the Louvre.

The cheapest and probably most efficient way for your son to get to the Louvre area from CDG is to take the RER to the Metro.

Below is a Subway Navigator. You can plug in the departure and arrival points and it will tell you which RER and Metro lines to take and where to transfer. I tried typing in CDG as departure point and it wasn't recognized. So I typed in Roissy and got two options:

Roissy/Aéroport Charles de Gaulle 1
or
Roissy/Aéroport Charles de Gaulle 2/TGV

I think international flights arrive at terminal 2, so I selected terminal 2 for you. Then Louvre came back with 3 options, louvres, louvre-rivoli, and musee du louvre. I just picked musee du louvre as the final destination.


Final RER and Metro Directions from Roissy/Aeroport CDG to Musee du Louvre:

http://www.subwaynavigator.com/subway_site/php/result.php?type=rls&pays=France&ville=Paris&station_arrivee=Palais%20Royal/Mus%E9e%20du%20Louvre&station_depart=Roissy%2FA%E9roport+Charles+de+Gaulle+2%2FTGV&langue=eng&id_ville=84



This is also the link to the main metro navigator page (below) so you can modify the the exact stops you need.


Subway Navigator main page:

http://www.subwaynavigator.com/subway_site/php/city.php?first=true&pays=France&ville=Paris&id_ville=84&langue=eng



Also, one more tip: There are kiosks where your son can buy a ticket on the RER, there was no line for this BUT you needed coins to use the machine - bills were not accepted. My husband and I did not have any change so we had to wait on line for nearly 30 minutes to buy a ticket from an agent (kind of like a token booth attendant). The plus side of this is that they all speak english (which is so welcome if you just woken up from taking an overnight flight and can barely even speak english, let alone trying out your french) and will give you exact directions on how to get to where you need to go. And it costs the same as the kiosk.

Hope this was helpful.

You might find this information helpful:

http://67.72.88.51/cdg

International flights arrive at both T-1 (US Air and United) and T-2(Continental, Delta, maybe American). Which terminal will depend on which airline - most likely one of the links offered above will provide the list.

To know which terminal:
http://paris-cdg.com/terminals.html

Ginny

How old and experienced is the son? If this is a neophyte, spring for the taxi. The RER is not a panacaea and it is not all that easy to navigate, EVEN if you have been to Paris MANY times. The fare will be in the neighborhood of 50E. It willdeliver him to the door of your hotel (I assume in the Louvre area) without his having to exit the Metro/RER and find the direction to the hotel. There is more to getting to your hotel than the RER.

You can also wait for him at a well-known landmark. How about this: have him take the RER to St-Michel Notre-Dame, and you all walk over and meet at the statue of Charlemagne in front of the cathedral one hour after his plane lands.

If you miss one another, the fallback plan is a taxi to the hotel.

We always take the RER. Faster, cheaper. But, we know where we are going and that make a difference. Give him some coins so he can use the self serve insted of lining up at the ticket wicket (though the line moves quickly).

I'll be leaving for Paris in two weeks and plan to use Airport Shuttle Service to go from CDG to a private residence in Paris. I used this service the last time I was there (5 years ago) and found the service an easy and inexpensive way to get into town. They drop off and pick up at hotels and private residences. I wouldn't want to take the RER because I'll have two suitcases and don't want to mess with getting them to the train, onto the train, transferring to a metro, etc.

I just checked Airport Shuttle's website and found that the rates are 25 euros for one person 14.50 per person for 2-3 people. You can reserve online:
http://www.airportshuttleparis.com/price_shuttle.htm.

The drivers speak English and most of the passengers -- at least 5 years ago -- were Americans. I first found out about this service through an ad in the Journal Francais d'Amerique, a newspaper aimed at francophones and francophiles in the U.S.

One caution: On the return to the airport, they were late. They excused themselves profusely and since I'd allowed plenty of time, I had no problem. However, I didn't have the time I'd planned to do last-minute shopping at the airport.