There is no way to answer this completely as there is a never-ending supply of sites, museums, people, shows, and events to suit everyone. It will also depend on your energy level, interests, and how long you are in Paris.

I never recommend that you plan more than one major activity a day, and even no more than four of them in a week's stay. 

This sounds kind of skimpy, but hear me out. Unless you are with an official tour, you will want time to be spontaneous. I also still under estimate how much energy it takes to get there, get in, participate, and how tired I am after I finish. It is also wise, especially if travelling with kids, to have "non-event" days to give everyone down time. If you over-book your stay, you run the risk of getting home and feeling resentful at how exhausted everyone is and how little you remember.

So, do your research and pick your top four activities (per week) that you must see and then choose secondary activities you want to do if you have time. Plan some "off" day things like picnic in the Luxembourg gardens.

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