Well, I find Vendak's idea a little extreme, but I do essentially agree with him. The problem is that a 'life sentence' can often mean 'fourteen years'. If you get this sentence when you're twenty five, you're not even fourty when you get out. Plenty of your life left for repeating your crimes. I do believe in a death penalty, but only where a completely secure life-long sentence is not readily available.
For example, two British find Bin Laden. They're a week's travel away from their comrades, having gotten separated and there is a high chance that BL will escape during the journey. I believe in this situation, execution would be the right thing to do, as it would be the only way to ensure that this awful terrorist could be stopped.
Contrast with this situation, where Bin Laden in captured by an entire platoon, less than a day's travel from their secure base. Execution here is unnecessary, whereas in the previous example, it was, in effect, a safeguard.
Finally, pain should neither be minimized nor deliberately caused during execution. The point of the death penalty is to stop that particular person, not to toture them. At the same time, resources should not be wasted in giving a criminal a more pleasant and easy death than most people will experience.