I understand your point. that being said, is there any reason why you don't feel comfortable having a handgun out of the gunvault when the grandkids aren't visiting? //example: knowing they are coming tomorrow so locking it up at bedtime(I'm guessing the vault is in master bedroom)
My kids are grown and gone but I have friends and family with kids that can stop by anytime. My dedicated HD gun is always in my handgun safe mounted to my bed frame. I never have to think where it is when pest control, cleaning service, or someone else comes over. Chances are, if I need a gun at home it will be in the middle of the night.
Plus, I always pocket carry a P3AT around the house so I don't feel the need to have any guns laying around or accessible to anyone. Like Vito said, it only takes once for your life (and others) to change.