We have tickets for the Eiffel Tower!! Daughter #2 had some questions. When I told her that Gustave Eiffel had his own office in the tower until his death, she asked "Great, can we see it? I want to check for old chewing gum under his desk!"
Great advice from a local: "Spend your money on breakfast and lunch in Paris because they are special. Dinners are like dinners anywhere."