I do not have kids of my own yet, but I do plan on it eventually.
I was only spanked a maximum of 3 times throughout my childhood, only one time I even remember. Every child is different. But if physical spanking is the only thing that gets through to them, then by god I'm all for it.
But if they are able to be successfully disciplined some other way, I'd go for that instead. As long as you know how hard to hit and how hard not to, spanking is really just a way to hurt their feelings to get it across that something they did was bad. At least thats how it was for me.