Paris looks lovely before the shops get busy. I'd start with a coffee and no strict timetable.
The Palais Royal has a garden, arcades and Daniel Buren's striped columns in its courtyard, just near the Louvre. [1] There is more than enough there to spend a slow morning.
I'd wear comfortable trousers, a shirt I really like and shoes that can handle a long walk. Pretty shoes are less charming when you can't feel your toes.
I'd probably stop to look at the windows, the doors, the little details nobody puts on a postcard.
That is my favourite way to imagine Paris. No costume required.
