How do venues cater to children and teens?

I have some kids (under 10) and then 8 cousins in their teens. I'm not sure where the wedding is yet (open to anywhere in Aus), but they make up a large portion of my guests so I don't want them to feel bored! Can venues supply mocktails for them so they can feel part of it and party with us? Should I be asking about kids rooms or somewhere where I can set up an xbox or netflix or something for them to do? Should I hire some games?