Your research is perfect-a one week pass runs from Monday thru Sunday and would seem perfect for your trip. However, getting the pass may be tough to do.

The Navigo is an electronically read pass in a plastic container which is replacing the Carte Orange, which is a small magnetic coupon. Both types of pass conferred the same travel privileges and cost the same.

The Navigo was first introduced a few years ago, and the Carte Orange will evetually be phased out. When we got our Navigos, they had to be mailed in to RATP and we got them back in about 10 days-obviously this won't work for you or anyone without a mailing address in France. I do not know if you can get a pass on a walk-in basis. Here's some info on where agencies are:

https://www.navigo.fr/pages/images/l...es_agences.pdf

Note that only a few are open Sunday ("Dim").

The Carte Orange is still around but to encourage Navigo use, they have stopped selling Carte Orange tickets at many Metro stations. I think the plan is to make it so inconvenient that everyone will go with the Navigo. Metro stations that do not sell the Cartes Oranges have a small sign stating that at the ticket window, but I don't know of any list of which ones do or don't.

If you're up for a little adventure, you could go to one of the agencies listed and see if they'll give you a Navigo right there. If not, chances are good (but far from certain) that they'll sell you a Carte Orange. If not, they might tell you where you can buy one-if they know.