I know they make a snap case that looks okay for the regular sized laptops, not sure about the air though. Ill look.
The laptops hold up pretty well so I wouldn't be too paranoid.
If you're worried about scratches you can put an invisashield (or whatever the term is for the clear plastic) but I think it would look weird.
Is your child going to be using it regularly or are you scared they will get their hands on it somehow?
You could buy a shock collar for the kid and condition him to fear the laptop.
and personally I wouldn't buy any of the LV bags, they look ugly and then you become one of those.