Juicy bags are definitely bad for trying to sneak your baby in anywhere -- it's soooo recognizable as a dog carrier.
I have a Kwigy Bo carrier - I like it, it's cute and roomy and lightweight w/storage for my stuff, however I have the London style and it's not really a good sneak bag either, although I don't really use it to take them places I worry about that
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I think the first bag is really cute and could pass for a purse, no idea on the ventilation though -- I think as long as you keep a flap up it should be ok
Hope that helps!