My husband and I are traveling to Paris with our 17,16,and 13 yr old daughters from Sun, July 8th - Mon, July 17th. We arrive in Eurostar and depart from Orly. Also, we plan to visit Versailles. What kind of ticket would work best for us? Do we qualify to get the discounted "Large Family" Pass? Where can we get it?
If you're planning on taking more than 4 one-way trips on public transit, per day, then definitely a Navigo Découverte for each of you. A Navigo Découverte will include Paris Metro, RER, in Paris and out to Versailles. The Navigo card will not work the evening you arrive though, as Navigo validity starts on Monday. Nor will it work on the Monday of your departure, as Navigo validity is strictly Monday to Sunday. To get to Orly on Monday, you can buy single-use tickets from any Metro or RER station inside Paris.
If you walk a lot and don't plan on using Paris public transportation much, then buying carnets of single-use tickets for Paris Metro and single-use tickets for RER trains is the least expensive option. Each carnet contains 10 tickets which is perfect for a 5-person round trip.
There are no large family passes, unfortunately. Children discounts only apply for those under 10.