I have lived there for 23 years. If I can recommand you something as a parisian. Don't go to the places that are full of tourist unless you want to. The beautiful in Paris is that you can get lost and find beatiful places. I have lived there for 23 years and I am still discovering new things.
If you want to visit the suburbs, I recommand you the Château de Chantilly or the Château de Versailles. But there are too many things to do in Paris that I can describe for hours. Just don't go to certain areas that are not recommand such as the Northe of Paris. 18-19th arrondissement etc. Be ware of your belongings.