We've been taking our son to Paris for the past 5 yrs(he's now 15) and you can easily spend the week in Paris with plenty to do with the kids. There are also day trips via bus that we enjoyed including Versailles(train to a bus), Veux de Vizcomte, Loire Valley(3 chateaus), etc. Last time there our friends who reside in Paris recommended the Segway tours of Paris which was great! I don't know what the minimum age is but they are easy to use and it was a great way to see the city on a beautiful day and that was over spring break this year. Have a wonderful time!