Hello. We arrive at CDG on a Thursday morning and taking private car to hotel in Versaille. We plan on touring around the town of Versaille on both Thursday and Friday. Then going into Paris Saturday and Sunday. We would use the Metro a few times while in the city to cut down on travel time with walking. We fly out on Monday afternoon with an airport transfer in private car again. I've read the many options that we have for tickets but now just confused on the most cost effective, stress free one to choose. Thank you for the help and your site is a wealth of information.
I'm assuming your hotel remains the Versailles one throughout the trip. In that case, I'd personally go with a Navigo Easy card (one for each of you), put several fares on it and use that for your entire trip.
The fares I'd put onto the Navigo Easy card are several Ticket t+ along with two Navigo Day Passes. I'll explain my thinking below.
For the Thursday & Friday, I'd guess that about 4 Ticket t+ per card would cover random bus trips around Versailles (there's no Metro in Versailles, only buses plus RER which is mostly just to leave Versailles, not travel within it). A Ticket t+ is the usual ticket for the Paris Metro or Bus or RER (in zone 1). Versailles is quite walkable and taking transit within Versailles itself is optional I feel and you may want even less than four Ticket t+.
For the Saturday / Sunday, I'd put two Navigo Day passes (1-4 zone) onto your Navigo Easy. Navigo Day passes can be anywhere from 1-2 zone to 1-5 zone and are good for unlimited travel for zones covered during their validity day (ends at midnight keep in mind). 1-4 zone covers Versailles so you'll be able to travel from your hotel into the heart of Paris, in & around Paris itself, and back, using your Navigo Day pass 1-4 zone, on your Navigo Easy. (Learn more about Paris RER fare zones.)
You can have two day passes on a single Navigo Easy card at any one time. You need to specify (at purchase time) the days the Navigo Day Passes are "active" and this can be up to 6 days in advance. So, you can do this either at CDG Airport train station ticket windows/offices upon arrival, or when you get to Versailles at say the Versailles Rive Gauche RER train station ticket window.
The additional Ticket t+ you put onto the Navigo Easy card can co-exist with the Navigo Day passes. The Ticket t+ fares will be used whenever the Day Passes are not "active".
If anything is unclear, please post another question and I'll be glad to try to clarify.