Bench press just won't cut it. Done properly in a powerlifting style (with the elbows abducted at 45 degrees) the barbell bench press is predominantly a front delt exercise. The more you flare your elbows to the side (abduct to 90 degrees)the more it targets the chest but also the more prone your rotator cuff will be to injury. Oh the dilema.
So here's what you do:
Solution number 1: Move to dumbells. Your rotator cuffs may be categorized as a stabiliser muscle but so can the chest or many other muscles. When you use dumbells the chest also becomes a stabiliser and creates more recruitment of muscle fibers. EMG studies have shown that dumbelss activate the chest far greater than the a barbell.
Solution number 2: Pre-exaustion. Lee priest, a famous bodybuilder would always start his chest workout by pre exausting his chest on cable crossovers then move to a bench press. The idea is that you fatige a targetted muscle group with an isolation exercise and then move to a compound exercise. The link in the chain of least resistance will have the most impact.
Have a good chest workout!