I've got 24 hours in Paris in July with my 14 year old son. We've done the Eiffel Tower, Montmartre, Sacre-Coeur, and the Arc de Triomphe before. We didn't do the Louvre last time, so we'll book tickets to take selfies with the Mona Lisa and the Venus de Milo (total expected visit time <1hr if we drag it out or the queues are bad).
