Obviously, the Eiffel Tower. If you go at night, the lights and city view is stunning.
If you enjoy shopping, there's a large mall(?) on Champs Elysees. It's been a few years since I was in Paris, but I can't remember the name.
Personally, I thought the Louvre was overrated. I LOVED the Impressionist museum and even the Rodin museum.
Johnny Depp owns a restaurant in Paris called Man Ray. I ate the most expensive dinner of my life there, (most was alcohol) but it was fabuolous.
At first, I wasn't impressed with Paris, I thought it was kinda dirty and kinda stinky, compared to Rome, anyway. But I grew to love it and was sad to leave.