Agree. The RER express train is easy even on a credit card from CDG and much nicer to walk around either Chatellet Les Halles ( Le Marias & Notre Dame is close by ) or the further stop as advertised. Gare du Nord is the stop for Montmartre.
Enjoy the AF lounge for an hour on your return but PARIS WINS in a heartbeat FRANKLY.
I am an English francophile and therefore love the food, the people & naturally all the French Ladies, what's not to love frankly! Enjoy Paris frankly and sleep on the plane after!
GO INTO TOWN as lounges get boring, even the quality AF one! AA lounge also good is my match report!