Opinions, Family itinerary in Paris final revision, I think!

Check out the Bato Bus. It's a water taxi of sorts, that you can ride and hop off and hop on. It runs a circular route stopping at most of the main sites near the Seine or you can just get on and ride the whole route. Good way to get from Notre Dame to the Eiffel Tower.
It can be hot in the summer, but in March should be fine. You buy a ticket and you can ride all day.

I'd skip walk down Champs-Elysees- nothing but big fancy stores, lots and lots of cars, long boring walk really.
I'd skip Montmarte and walk Latin Quarter or Marais
I would add Notre Dame and St-Chapelle, I think even a 20 month old would be mesmerized by St-Chapelle. Neither take a huge amount of time.

Thank you
I agree about the Champs, my wife is convinced it will be beautiful. Do you a have an alternative I can suggest to her, maybe around the opera?

I’ll definitely try the water bus, I love the rivers in Europe!

The main thing is to get a great feel for the city and not at burn out pace for the family.

Agree with Christine, St Chappelle should not be missed.

I disagree about skipping the Champs Elysees. While it is touristy it is also iconic and worth a walk. After you leave the Louvre I would walk through the Tulieries gardens to the Place de la Concorde and then up the Champs Elysees to the Arc de Triomphe. It is all on a straight axis. On a clear day, from the Arc de Triomphe you can look down the Champs Elysees and see the Obelisk and through that the Arc du Carrousel, an arche half the size of the Arc de Triomphe. If you look in the other direction, you will see the Arche de la Defense, which is twice the size of the Arc de Triomphe. It is pretty cool to see. I would not, however, have lunch along the Champs Elysees. Restaurants are expensive and touristy and not necessarily very good. Perhaps after the visit to the Louvre you could get a snack at a patisserie (most have sandwiches as well as pastries) and have a picnic in the Tuileries garden. I would then have an early dinner in the Latin Quarter. It is a little bit of a trek to Montmartre. I would save Montmartre for perhaps the 4th day.

On the Champs Elysees, if you like mussels and fries (moules et frites) there is a Leon de Bruxelles about half way along.

I'd second walking Latin and St. Germaine quarters. But, I wouldn't discard the idea of walking the Champs de Elysees. I don't like shopping and I tend to avoid masses of people, but I enjoyed the walk for the Arch de Triomphe to the Tuilleries. I paid attention to the views around me and the architecture. I also enjoyed a short time at the Arch de Triomphe.

See Paris without a look at the Champs? Never. Sure it's tacky and crowded and all of that but as others point out, it's iconic. If you can disregard all of the negative, the view all the way to La Defense is something. The great axis of a great city.

Thanks everyone
Looks like the Champs elysees stays in.
Have you walked from the gardens outside the louvre to the arc? Would that take about an hour at a relaxed pace?

Google Maps says it's 48 minutes from the Louvre to the Arc de Triomphe, and I've found it's walking times generally realistic. I'm a pretty fast walker, so 1 hour should be about right for strolling.

The special thing about walks in Paris is that they can take as long as you want them to. Don't miss this spectacular on your stroll and maybe read up on Les Grandes Horizontales

https://en.wikipedia.org/wiki/H%C3%B4tel_de_la_Pa%C3%AFva

It took us less than an hour.

Before I comment I have a question. Does your 20 month old still nap? If so some of your days may need to be adjusted.
And keep in mind, if the children are going to have different interests, you could split up for some of the partial days.

Have a Great Trip!
Mimi

Our son still takes naps. They are getting shorter and less frequent. He’s super active and curious so I’m sure he’ll love the parks and he’ll love watching everything around him. I’m planning on him sleeping in his stroller for some of the walking and probably heading back to the hotel a couple of time during the trip.

Take the metro to the Arc de Triomphe and walk down the Champs-Elysees. Much easier to push the stroller down rather Than Up.

IMHO you would miss a lot by taking the metro to the Arc de Triomphe and just walking down the Champs Elysees. It is a VERY pretty walk from the Louvre and pretty flat. I don’t think pushing a stroller would be an issue.

Thank you all for the tips.
This really helps a lot.