Paris is a place where once you come you always return. Here you will be able to walk and to climb in so many places that you did not visit last time or that you want to visit over and over again.
Going up to Notre Dame you will see one of the most beautiful views over the city. Here you will eat lavender ice-cream. It tastes very well and the lavender is used a lot as a flavor in the food. Using the Open Tour busses you will feel the beauty and the bohemian Paris. The next stop can be in Place de la Concorde, where you will see wonderful fountains.
You will pass near Louvre but there is no reason to enter it, as you will not have enough time to view it all. It will take more than 3 months to look and analyze and understand the entire art that Louvre has inside. Until seeing the Eiffel Tower you will not feel it as great as it actually is.
What you should be very careful about here are the thieves. There are many thieves that like doing pranks and they stop at nothing. Having a person or two besides you will prove to be more than a blessing.