Anonymous wrote:DS and his girlfriend did this last summer. They had a 9 hr layover in CDG on their way back to the US from Asia.
They left their carry on luggage in lockers at the airport and just carried a small backpack or such (the personal item) with them. They took the train from the airport into the city and it was very convenient. They would not recommend taking a taxi as traffic can be pretty bad depending on the time of day.
They gave themselves 4 hrs of actual sightseeing. They just walked around and looked at a few landmarks from outside: Eiffel tower, Notre Dame, etc, walked along the Seine, stopped at bakeries and cafes, just taking in the city.
They made it back to the airport with plenty of time to spare. They said they could have spent more time in the city, but they also said it was tiring because their flight into CDG had been an overnight flight and they hadn't slept well and, well, the time difference did not help either.
So it can be done, but absolutely needs to be planned ahead of time. They had researched everything, the train lines/stations, train times, etc, and had an idea of the places they could see using a combination of train rides and walking. They also had euros with them before they traveled so they did not have to spend time converting currency at the airport. Also check for current visa requirements for American citizens. I think they were going to change this year, but I don't remember when.
There is also a lot of information on Reddit. Good luck OP, I hope you are able to see at least some of the city!
Yes this is the way to do it- but you probably won't need any euros for an afternoon like this, pretty much anywhere you will want to stop will take cards. Probably easiest thing to do is buy a one day Paris Visite metro pass, which is normally an awful deal, it's 30 euros for 1 day/person, but since the ride to/from the airport is 14 euros each way, and each ride in the city is 2.50, it's a reasonable deal. Assuming your 2nd flight is inside the Schengen zone (most of the EU), you can arrive back at CDG around 90 minutes before your flight, since you won't have to go through passport control or go to one of the really far out concourses.