La Tour Eiffel,
Galleries Lafayette, go to the top of the store and see the view, also note that on every floor of the store is somewhere to eat and drink, on the childrens floor, is a McD's ( sad but funny halfway up in a big dept store)
Versailles is absolutely beautiful, the gardens have all been restored, I didn't bother going in the hosue as the gardens are spectactular and free,
Take a river baton down the Seine too, fabulous views of Paris,
The Big Wheel on Place de La Concorde, also worth a view
If you can leave Paris, go to Giverney, former home of Monet and see the Gardens where he painted