It's hard for a brain (maybe just my brain) to come up with unique scenarios. Generally the same ones are revisited and revised in my head until I cum.
I can feel the sensation of his hands on my skin, caressing my legs as he enters me. His eyes fixed upon me and his smile, he nods as he reaches deep inside me. This scenario is sweet, it never makes me cum. This is the foreplay. What makes me cum is thoughts of the naughty stuff. It's odd though, if I think about it, because this stuff is most likely to make me cum in real life, the slow attentive fucking. I think this means that I get off more on what gets him off.
Sometimes I imagine myself on my knees in front of him as he sits or stands before me. I worship his cock. Sometimes I look up at him and speak, asking him to fuck my mouth or my pussy. Sometimes I'm quiet and let him guide my head further and further down until I can't breathe.
Other times it's a loop sequence of him taking me from behind bent over the desk in the first room we fucked in, the desk with the mirror in front of it. It's violent and rough, banging fast. Smacking into my ass making me moan as I watch everything in the mirror. One of his hands is grabbing my hair pulling my head back, stretching my neck.
It's my own hands moving over my skin, grazing and caressing, pinching, pushing and grabbing to reach the same completely different goal.