First off if you go to a fucking museum you deserve to be decapitated on live television, but if you insist on going to an art gallery, or museum leave the kids at home. If they are young enough to do shit like this they aren't old enough to appreciate art. They are going to be bored, and all they will do is cause trouble. Leave them at home guys.
My parents took my brothers and I to museums and art galleries when we were children instead of tossing us outside with a ball and locking the door. We're better, more open minded, loving, and cultured people because of it.
So if you want to ban children just so some aged greying hippy can stare at a bunch of shelving units in peace, don't expect the world to be an overall better place because of it. Expect the museum to be bulldozed to make room for a McDonalds play place once the kids who never went there grow up.
The problem with modern art is there's more people than ever before "Trying" to become a professional artist. And when you can tell somebody is obviously trying to become a professional artist, it just completely saps all of my interest away in their art.
I personally like to collect period Mexican sweat shop velvet paintings, and other such art. These people were just trying to make a quick buck to feed their families, and yet on some of them, you can really see and feel some very amazing brush work, especially on the less common designs.