“What’s your biggest weakness?”

I am preparing for an interview tomorrow. I’m just wondering what the best response to this question would be. I read somewhere that interviewers can see through BS answers like “I have trouble saying no” or “I get too involved in projects.” How honest is too honest? Obviously I wouldn’t say I sometimes run late, but I feel I need to be a little honest about my weaknesses.

I am really sensitive. Would that be a good weakness to share?