Agree. I've thought about this a lot, and I now find myself compelled by the 'silent murder' scenario. It seems likely the entire annihilation was pre-planned (he fits the profile), and as such, CW would have wanted quiet and control. The best way to accomplish this would have been ZERO drama. We've certainly seen how the close proximity of the neighbors houses could have been a risk to CW during the crimes. Imagine a mother encountering dead babies as she went in to kiss them after arriving from the airport. She would likely have screamed and then fought, and CW would have lost control of the situation and the noise could have been heard by neighbors. CW could not risk confrontation and loss of control. To avoid this, everything should appear normal to SW when she returned. Then he could attack her unexpectedly from behind, when she was most vulnerable, perhaps as she was sleeping.
Having been successful killing his wife, he was 'in for a penny, in for a pound'. Entering a machine-like dissociated state of a sociopathic killer, he proceeded to dispatch his girls, perhaps with pillows so they would also be silent and he would not have to look into their faces while they were dying at his hands.
Interested in any evidence to the contrary of this scenario!
Makes one shiver to consider it all...
Dave