Facial expressions can reflect a vast amount of precise emotions and feelings, a perfectly clear window to what is inside. At this point you know that nothing else matters and she is consumed with feelings. Perhaps it is this that enables women to be far more self aware than men, and far more emotional. Having said to be able to connect emotionally is very important, eye contact is of major importance too and allows the two bodies to connect emotionally.
With a womans legs over your shoulders and leaning forward is the best position to enjoy the look of the womans face as she cums, this position seems to produce very intense orgasms, mainly because (I believe) the man is in full control, emotionally and physically. Try it next time and see if you agree with me.