I suppose the most obvious difference between Buffet/Gates, and Waltons, is that they recognize the pretty godamned obvious. The fact of their children being their children, doesn't have a whole lot of bearing on their ability to run their companies. In fact, it doesn't really matter how smart, well-educated, and familiar they are with these bidnesses. The odds are remote, that they'd be the best candidates to lead these companies into the future. And of course...I'll betcha that they realize that an always-filthy-rich kid, doesn't have quite the motivation that they had, or that someone from outside the family might have!
So, Buffet/Gates DO recognize that like it or not, money IS power. There's no way in hell either of these guys could come even close to spending all their dough. So, why don't they just give most of it away? Well...they DO give a bunch away, but they hang on to way more than they absolutely need because again, "money is power". And in the case of Buffet/Gates, I like to look at it as the "power to do good" and I imagine they do to.
So anyway...as to estates, both have quite publically limited their familial heirs to but a tiny fraction of their wealth. I don't know what the number is but hey...$100 Million is a tiny fraction of THEIR wealth! And in doing so, they're passing on comfort and opportunity, but now power. If their kids want power, they need to earn it for themselves.
So.....the Walton heirs? What does THEIR inherited wealth represent and how are THEY exercising the power inherent in it?