For some reason, the word man/woman bothers me. I can't really explain it, but I guess I tend to think of man and woman as the older generations rather than 18+.
I like using boy and girl, but then again, my characters are only 19 and 21, so they could pull it off.
I've never tried writing adult novels, so I don't know how it would feel to use man and woman. Thinking about it now, it would feel more right than using it in my current novel.