I am not a parent so I can't say what I do or what I will do in the future, but speaking from experience, all three kids in my family were given some form of corporal punishment at one time or another. Most discipline was going to your room, a time-out, deprivation of activities, but we were only spanked if we persisted in our defiance.
One particular instance will be with me for the rest of my life. My mom washed my mouth out with (liquid) soap because I told her to "shut up." She had told me that if I ever said that to her again, she would do it. Though she regrets it still to this day (and I still remember the taste! Ugh!), she said she had to follow through or else her position as a parent would have been continually undermined. Plus, I think it actually got my brother, who is way more the trouble maker than I ever was, to straighten up and fly right.
When used in moderation and used to stifle negotiation and defiance, corporal punishment works effectively. I think that my brother, sister and I turned out fine. Would we have if we were not spanked? Who knows, but I kind of doubt it.