Looking at these two examples

http://www.exrx.net/WeightExercises/...enchPress.html

http://www.youtube.com/watch?v=wSjn4cDg4VI

One uses shoulder-width grip, one uses a grip of about six inches apart, which do you use, and why? I tend to go closer then shoulder-width to really isolate the triceps and not bring the pecs too much into the lift.
Thanks.