We arrive Monday at CDG, would like to head to central Paris for a couple hours, then we need to get to Paris Montparnasse train station. It possible that we may use the metro within central Paris if time permits.
1 answer
A Ticket Mobilis 1-5 zone would be your cheapest/best pass option for a single day including CDG to Paris and riding Metro within Paris. There's no card fee with this option, like there would be for Navigo Day Pass.
https://parisbytrain.com/paris-metro/#mobilis