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We took our children to Paris twice. Once when they were 5 and 2, and once when they were 14 and 11. I think you will have a great time as long as you don't try to see too much each day. Of your potential sites: My kids enjoyed going up in the Eiffel tower, the Seine River Cruise, and the Luxembourg Gardens. The Louvre was too much much when they were young. Some things that worked for us that you may consider: The Paris Metro is fun. I would take that instead of a hop on hop off bus. Renting an apartment is nice and lets you have a refuge for preparing some of your meals and doing a load of laundry. The Orangerie museum (https://www.musee-orangerie.fr/en) was an unexpected family favorite. It has huge Monet water lillies paintings, and oth...

I think you have a good plan to spend some time in Paris first, and then head to Normandy.

DW and I visited the D-Day beaches on a shoestring budget and drove around with a guidebook. We went back decades later with our kids and got a guide. The guided trip was a much better experience for us.

If you have your own rental car, I recommend hiring a guide that will go along with you in your car. Our guide was Magali Desquesne, and she was great (we have no connection to her). If you do a web search you could find her, but I bet other guides also have the same kind of tour. We had four people for a tour, and by driving our guide in our rental car, it was less expensive or at least comparable to a group bus tour for the four of us.

+1 on the Ghost Whisperer for being incredibly lightweight and stuffing down very small, but the fabric on mine is so lightweight that I don't know how long it would last for use in town on a regular basis.

Not what you asked, but if I wanted a lightweight and high quality down jacket at a discount, I would look at the following websites: steepandcheap.com, sierra.com, campmor.com, and rei.com/rei-garage You can often get expensive brands at a large discount, although often only a few sizes or unpopular colors have the best discounts.

+1 on sizing up and +1 on the speedgoat. My Hokas are 1 size larger than my other shoes.

+1 Air and Space museum
+1 Spy museum
+1 moonlight monument tour (recommend early on to get the lay of the land)
You likely know, but check the websites of your Representative and Senators as soon as you know the dates of your visit for tickets to things like the White House and the Capital building.

Our son was around 10 at the time of our visit and it seemed like a good age.