but with those ages don't worry much about a lot of time in huge museums.
US News does a good job with their articles of "best of" for varies cities. Check these out and decide what would be the most meaningful. Sounds cheesy but with so little time, I'd take a hop on hop off bus to see as much in as little time as possible. It gives you the main sites then you can get off to see what you want. The dusk river tour is great too.
https://travel.usnews.com/Paris_France/Things_To_Do/