Since I'm assuming you want to work in PR or Advertising, I don't think you need to worry about your preference for slacks. I personally think a woman can look fantastic in a well cut pants suit; not "masculine" at all.
I don't know how common this is, but a former neighbor is an attorney and she mentioned once that, whenever she appeared in front of a certain judge, she always wore a skirt suit because everyone knew that he didn't approve of females in pants
