Another idea is for everyone to take the RER B into the city and get off at St. Michel/NOtre Dame and take the elevator or escalator to the surface and walk around the center of Paris. -- the central Islands and are lovely, the Hotel deVille is impressive -- you can get coffee and drink in the view and walk around a bit along the seine. The central islands have lovely parks and you can enjoy great views of Paris -- and then get back on the train and go back to the airport. It is IMHO the lowest risk/biggest payoff approach if you have limited time and want a. glimpse of Paris.
The only caveat is that you must be pickpocket proof -- I personally would use an under clothing money belt for passports and valuables on such an excursion. Tired people who don't understand what a skilled pickpocket can manage are at great risk -- but if you make sure nothing is available in pockets or carelessly held purses you are good. (waist packs, backpacks and such are a pickpockets dream)
It is not difficult to be pickpocket proof, but it is necessary especially when you are needing to catch a plane.