Arnold Schwarzenegger had one of the biggest and most spectacular chests in bodybuilding history. The secret of his big chest is not about the exercises that he was doing, but about the way he did them. The most important thing in his workouts was always doing a full range of motion.
Nowadays many people who just joined the gym are focusing on progressing with weights and they dont really pay attention to improving the technique. Often it is better to decrease the weight and do the reps having a full control of the barbell.
One of Arnold's favourite exercises were lying dumbell flies. The range he had was very impressive, because his arms with the dumbells were almost perpendicular to the floor. To isolate his muscles even more he was raising his feet and bending his knees.
The exemplary chest training in Arnold's style:
barbell bench press - 5 series of 12,10,8,6,4 reps,
barbell incline press - 5 series of 12,10,8,6,4 reps,
lying flies - 4 series of 12,10,8,6 reps,
chest dips with weight - 4 series of 12,10,8,6 reps,
straight-arm pullovers - 4 series of 15 reps each.