Does your s/o like to watch you masturbate? For years, my wife always told me that watching me jerk off was boring. Then, after getting into anal/prostate stimulation, things took a different turn. I told her that it felt really great and she wanted to see what I was talking about. She wouldn't do it, but she said she would watch. My wife became facinated at seeing a big dildo going in and out of my ass. I also found a new excitement in doing it while she watched.
I have masturbated while my wife watched. I was usually sucking her tits, or eating her pussy at the same time. It is not a matter of whether she wants to watch, but of whether I want to do it. She knows that if I need to get-off I want to share it with her even when fucking is not an option, so I come to her with my hard-on and expect her to participate as much as she can.
I agree with the anal, however it seems to take forever to prepare before and cleanup after... I'd say the whole process could easily take 3 hours.