David as I am a Brit may I give you my take on this. As the density and contrast are effected by an enormous number of permutations from exposure to print, not least a subjective and personal preference element, together with what the picture is/context/mood/etc., an ideal negative can’t really be defined. Having said that, for me and I should imagine for most people (but perhaps not all those on APUG), an ideal negative is one that is easy to print with little or no intervention. So with a consistent processing procedure and printing usually on a condenser enlarger, I find a negative slightly on the thin side is usually ideal.