Adam:

doing bench presses on inclines, declines and flat soes not build muscle soley in the "regions of the chest". They recruit more muscle fibres from these areas but the dont provide any real benefit IMO.

The chest, when fully built will look like a balloon, it will have curves and the illusion of upper, lower regions.... this is an illusion.

I had a 46" chest at one stage and i never did a decline bench press in my life, but my "lower chest" was fine. I did incline work but that was to take stress off the shoulders.

To build the "upper & lower" areas you need to work the chest as a whole, not a sum of its parts.

Bench press
Incline DB bench press
Dips

substitute dips for DB flys every now and again

PS: i know there are two heads of the pectorials (major + minor), it is impossible to isolate any muscle group, just keep on working out and when your diet and training regime are in a good state, thats when your chest will grow