So interesting! I love seeing the range of turn-ons in this thread.
For me, much like another had mentioned earlier, when it comes to the physical I tend to react to a rather narrow set of qualities in men and have a much broader field of traits I find attractive in women. I used to sort of actually feel bad about that, like I wanted to force being a "midline bisexual" instead, but it is what it is and time has shown me that I'm not so rare. A large number of androgynous and fluid people also get me going.
Across the board, I'm into hands. Wrists and forearms, too. I have large hands myself and I tend toward someone with comparable ones, lol. Whether large or small though, it's the way someone uses their hands that gets to me, little gestures and mannerisms, hands that appear to have "creative" talent and can use different dynamics of strength/softness. (FYI, creativity as a whole is a huge psych turn-on for me). If you can wear the hell out of a nice bracelet, ring, watch or (insert swoon here) a GLOVE... Oh my, I just melted.
Guys: Give me nice eyes, especially blue or green, bonus if they look great with liner on. Hair that is long enough to fall over me, else go sharp and bald. I'm admittedly hotter for the taller ones since I'm 5'11". I like to look you in those pretty eyes.
Ladies: There's not much I don't like, haha. Every time I think, "well, I doubt I'd be attracted to THAT in a woman", along comes one to turn my head and change my mind. I thought that about fake boobs for example and had to stand corrected years later.
Different women bring out different parts of me, which I love.
The mental/intellectual turn-ons... boy, I'd need another whole post!