Went to Paris last weekend. Highlight sights of the trip were the Musée des Arts et Metiers, returning to the carnival we used to go to when I was little, and the catacombs. Dad and Cha, when you go later this month, definitely check out the museum at least. It's one of the best I've ever been to, and totally uncrowded. The carnival may or may not still be running by the time you get there, but it's completely unchanged and super fun. (Catacombs are incredible but might be a bit grim for the kids.)
Here are some pics: