Technically, having the absence of pain throughout your body and mind is the fullest pleasure. Practically, I'm not sure that I've ever experienced that! Maybe when I was a baby?
In any part of the organism, once all pain is gone you can experience increasing pleasure in that part, at least until the increased sensation causes pain. So, interestingly, the maximum pleasure of the entire organism is the absence of pain, whereas the absence of pain is the minimum of pleasure for any specific location in the organism.
This explains the interaction of intensity, location and duration. The location of the minimum pleasure in every location throughout the organism is considered a greater pleasure than the most intense pleasure in a few parts of the organism. Practically speaking, this provides some guidance for maximizing pleasure through working with all three of the components instead of just the component of intensity.
(oops, we cross posted)