Paris 7 days mid week arrival metro/RER pass- Navigo ticket questions/Advice

I probably wouldn't buy a Navigo for 1/2 week; truthfully though I've never purchased one because the math never seemed to make sense. I typically buy a carnet of Metro passes for most transportation and get a second when I need it. I walk any time the trip is less than 15 minutes, because it will take that long to use the metro (longer if there's a line change). For CDG and Versailles, you can buy the ticket you need at the station. The price is reasonable.

I do like the Museum pass. I'll have a loose plan for sights which includes mapping out closures and/or free days to ensure I don't have an active museum pass when I can't take advantage of it's value. It's typical for me to plan to use a museum pass some days, then either visit free sights, sights not covered by the pass and/or parks on the other days. I never want a museum pass on the first day off the plane. That's a better day to be outside in the sun doing plenty of walking to stay awake and recover from jet lag.

The airport trip CDG/Paris is 10.30; round trip to Versailles is about 8 Euro -- the weekly charge on the ND is 22.50 or so and the card purchased once every 10 years is 5 Euro. To me this would be a no brainer if your Versailles trip is in the first week. For the second week you can let your previous experience guide you. If you use the metro less than you expected, then perhaps just share a carnet of 10 metro/bus tickets for this second leg for 14.90. You will at least break even on the ND that first week with moderate local use and those two our of town trips.

I agree with the previous poster. I didn't recharge my Navigo for my last few days in Paris once and I really regretted it. The Navigo is so much more convenient than tickets, allowing unlimited travel and transfers. It is likely you will use public transportation more often than you think, and the RER ticket to CDG is half the price of the Navigo. I vote to recharge it.

Seconding Carolyn’s post above. The convenience of the Navigo especially during crowded rush hour metro times, and not having to think about whether you have enough paper tickets left. If you go Navigo, it’s really helpful to bring your own extra passport photo for the Navigo pass, as I had a laughable (and expensive) experience before I ended up selecting the correct size in the photo booth that they have in the metro stations where you can buy the Navigo pass (which you can’t do in every station, btw, only the bigger ones).