Hi Geoff,
Paris is such a beautiful city
Marc Monceau, near to the Arc was the site of the first silk parachute jump in 1793. There is a little commemorative parked tucked away between some bushes. The parc is perhaps my favourite spot in all of Paris - and hardly has any tourists - just lots of joggers on Sundays!
If you are visiting the Louvre, there is also a nice astronomy shop near by. I cant remember the name of the shop - I think it was somewhere along Rue de l'Opera.
We are toying with the idea of visiting Paris again next month, but we pay delay until next year when our baby is a little older.
Have a great time!
Kind regards,
Andrew