I know some people who have and like the sheet-metal Snap-On locker safes. They would suffice for keeping visiting children out.
As far as burglary provention, even the biggest may not stop a determined thief, but I am reassured that my Liberty Safe would deter someone looking for easy money. Nothing in it is anything irreplacable, though.
I also have one of those finger-coded electronic safes for the carry gun by the bed, for when I'm not holding it. It is fast, simple, and keeps the kids out.
Also have a "Mosslock", a gun lock that pretty much bolts to the wall to keep a shotgun ready but inaccessable to children. Concealment instead of cover is a good way of thinking of it.
It is a tradeoff for inaccessable to burglers while I am not home vs. accessable to me and not the kids when I am home. Again, no priceless artifacts that can't be replaced from any gun store.
An alarm that will automatically call the police may also help deter your big heavy safe from leaving.