I agree. It is a wonderful experience for both parties if you
hold her breasts from behind and your erection is pressed between
her butt cheeks. She will feel stimulated at 2 places at the same
time, top and behind. When she squirm with pleasure her buttocks
will clench and relax, her hips will shift and press into your dick
such that you can feel every clench and relax of her ass.
Of course, she must be of your height, with a meaty and firm rear
and is wearing a thong with very little else.