It is usually a nice ass in tight pants that I notice first. In fact, that was the first view I ever got of my wife!
I was a supervisor where I worked and one day I heard that three new employees had been hired and were training to work in one of my departments, so I went to the classroom to introduce myself. They were sitting in chairs, facing away from me when I entered the room and there was enough space between the seat and the backrest of the chairs that I could see their butts easily. The employee that would eventually become my wife was wearing a tight pair of Levis and looked awesome! I don't have a photo of the view I saw that day, but it doesn't matter because it is burned into my memory!
This is a photo of the butt I saw that night, taken about a year later!