We have an Tuesday 11 am flight out of CDG. We're staying in the Rue Cler district in Paris. Is it better to use the metro or a taxi to get to the airport in the early morning? I can't tell how long it will take on the metro versus a taxi.
You can take the metro to the Opera station (4-5 stops from Rue Cler on line 8) and then transfer to the Roissy airport shuttle bus, which will take you directly to CDG. Whole trip normally takes about 90 minutes. Roissy bus runs every 15 minutes. Taxi is usually around 45 minutes depending on traffic conditions, and way more expensive.
Take metro line 8 from either Ecole Militaire or La Tour-Maubourg to Strasbourg - Saint-Denis. Transfer to metro line 4 and take it to Gare du Nord. Transfer to the RER B and take it to either CDG 1 or CDG 2 TGV. The trip will take one hour and the fare is €8.70. Be aware that the RER B line divides northeast of Paris. Be sure to get on a train that is going to CDG.