Notre-Dame and Sainte-Chapelle in the morning, the Louvre’s courtyards and the Tuileries after lunch, then the Seine at dusk.
Day 2
Left Bank
The Musée d’Orsay, a walk through Saint-Germain and the Luxembourg Garden, and tea at the Grande Mosquée.
Day 3
Architecture day
Fondation Louis Vuitton in the Bois de Boulogne, then the Bourse de Commerce and Fondation Cartier near the Louvre.
Day 4
Marais & the Arab world
The Marais, Place des Vosges and the Musée Carnavalet, then the Institut du Monde Arabe at sunset.
Day 5
Versailles
A full day for the palace, the gardens and Trianon. Start early; it is busiest late morning.
Day 6
Montmartre & canal
Sacré-Cœur and the Montmartre lanes in the morning, then Canal Saint-Martin and the Parc de la Villette.
Day 7+
Go further
Giverny before it closes on 1 November, Chantilly, Fontainebleau or a day at Disneyland Paris.
Honest thought: Paris rewards slowness. Plan one area per half-day, book the big museums for opening time and leave room for long lunches and walks between them.