CDG Connections

It is not a connection unless it is on one ticket. I would not book a separate flight with less than 4 hours. One immigration and customs and whatever and the usual 3 for check in and security for ongoing flight. While 2 hours is usually enough for a domestic flight, enough things can go wrong that you need a little cushion for late plane and such. If you try to book a second ticket the same day, you need to be mentally prepared to buy a new ticket. Remember that check in usually closes on budget airlines at least 40 minutes before a flight -- so making it 'just barely' is not an option.

I don't like tight connections. It's no fun to be running through an airport with my stuff, covered with sweat. I don't want to have to plead my case to surly airline employees. If I can, I fly nonstop. I see that you cannot for these cities, but I would pick another connection. How about United from DCA, connecting in Brussels - 2.5 hour layover on the way out and 3.5 on the way back. I haven't transferred flights in Brussels but it HAS to be better than CDG.

If both flights are on the same ticket as connecting flights, the airline or ticketing agency presumably has your connection conforming to the airline's minimum legal connecting time and would be responsible for getting you to your final destination. That said, 90 minutes in my limited experience with CDG is a tight connection even if your inbound flight is essentially on time.

While you should not need to clear customs, passport/immigration control and security rechecking at CDG is like a French dinner in terms of speed. If your inbound flight and outbound arrive and depart from different terminals, add time. The EasyCDG website recommended minimum connects seem accurate:
http://easycdg.com/passenger-information/connecting-flight-connections-paris-cdg-airport/transit-information/

Minimum transfer time recommended by ″easyCDG″ :

• 60 minutes intraterminal 1/2/3

• 75 minutes between terminals 1 and 2

• 90 minutes between terminals 1/2 and terminal 3

Of course, that assumes that your inbound from the States arrives substantially on time. Fortunately, in my limited experience, overseas flights seem to have build in delay time for headwinds, moderately late departures etc with all bet off if there is a big problem (snow, equipment issues etc).