For me I'd have to say belly button (especially a pierced one). That and also a girl with her hair in a ponytail.
My wife and I will pee when we are both in the bathroom (not all the time). It doesn't turn me on but I'm comfortable with it
Only usually when she's nearing the end of it
Having 2 days in a row off
Listening to some music
Spending time with my family
Relaxing
My wife was extra horny while pregnant. It was rather good ;)