My wife's has always been a younger man. Much younger, like 18 and most especially a virgin. She wants to let him fuck her raw and see just how fast and how hard she can make him cum. And it would be best if he was a heavy cummer.
Mine, in addition to watching hers...
I want to tie her spread eagle to the bed, blindfolded, and watch a guy or two or three fuck her. Blindfolded so she never knows who's in her. I'd especially kind of like to watch her best friend's husband fuck her. She knows he wants to have a go at her, she doesn't know he's already seen her nude and every time I see him asks if I've talked her into swapping yet.