Don’t go to the top of the Eiffel Tower
Similar to the Empire State Building in NYC, going to the top of the tower is overpriced and not as worth it as you think it will be. See the city from up high from the top of the Tour Montparnasse and actually have the Eiffel Tower in your view, or head to Montmartre for a sweeping, totally-free skyline.
Visit Versailles... if you have time
If you’re a history buff knock yourself out, but it’s expensive and the line to get into the palace is absurdly long. The better option is to wander the grounds for free on a sunny day.
Budget a whole day to get lost in the Louvre
See Venus and Mona, of course, but do not leave without walking through the lavish Napoleon III Apartments. The place is enormous -- wear comfortable shoes.
See Monet’s Water Lilies, then picnic in the Tuileries Garden
The tiny Musée de l'Orangerie in the southwest corner of the park is the permanent home for a handful of works by Picasso, Chaim Soutine, Modigliani, Matisse, and, the pièce de résistance, eight giant panels of Monet’s Water Lilies. It won’t take you more than an hour or two to see everything so pair the visit with lunch in the garden.