If you don't mind a crowd Les Invalides and the Louvre are great. Les Invalides is a MUST see if you enjoy history especially military history. Amazing amount of armor in that place.

If you're into more low key things I suggest the Picasso and Impressionist museums.

I didn't go to 'Moulin Rouge' as I heard: it was a tourist trap, in a bad section of town (Sacre Coeur), and I just wasn't into that whole deal.

It all depends on what you and your wife enjoy. Expect 50 billion asians taking pictures 1 at a time in front of everything....just take 1 picture, you all look alike!!!!

....Ooh do try the gelato AND the crepes with Nutella and bananas. You'll love Paris if you're a foodie.