Earlier on I saw a post from a lovely woman moving to Monaco with her 3 children .. looking for family activities. It took me a while to locate the info I thought she could benefit from - but now I can't find her post!
So, in case she is reading the forum again ..
There is a great martial arts school .. even if your boys are as young as 3 they can begin lessons. It's quite family oriented and a great way to meet other parents for home playdates, etc.
Here's the link:
monaco-arts-martiaux.com
My 3 yr old son also like going to tradeshows believe it or not! It's a great outing since every few meters someone wants to say a big smilely hello. There are tons of tradeshows in Monaco, lots of fun for the family if your boys love short-term busy interaction.