There are a couple of Companies that do Bus tours of Paris I think...or maybe only one but it doesn't really matter as they are mostly the same. These are the fastest and best ways to see all Paris has to offer. You can jump on and off and different stops and your ticket is valid for 24hours so if you buy the ticket at 3pm it will be valid till 3pm the next day.
You will see all the major attractions including The Eiffel Tower, The Louvre Museum, Notredame, Champs-Élysées etc etc
