Not with kids of my own and it being a while since I was that age, I'll leave it to you to decide, but Wikitravel's New Orleans page lists several childrens' attractions in the city:
- Audubon Zoo (Audubon & University District)
- Aquarium of the Americas (French Quarter)
- Louisiana Childrens' Museum (Central Business District)
- Storyland Amusement Park, City Park (Mid-City)
- Streetcar rides -- many children from cities without trams find riding on an old streetcar an interesting novelty in itself -- and parents can enjoy the scenery and historic architecture.
I can attest to finding Melbourne, Australia and Christchurch, New Zealand's trams to be quite the novelty when I was younger. When I was older too, but that was when we hired the tram out for company drinks :)