Work dress code opinions?

Hey everyone, I have a couple of questions to pose about work dress codes and what is and is not appropriate.  My work is "business casual," which is very vague. My questions for you are:

1. How short is too short for a skirt?  Our policy says only that it needs to be appropriate for work and no mini skirts.  A lot of skirts/dresses fall mid-thigh on me because I am 5'11, and I am not sure if that is okay for work.  I still have the same length of leg covered, I just have a few more inches below the hem than most women.

2. How low is too low-cut for a top?  Our policy says "no cleavage."  Well, I am very small-chested and never have cleavage, so how low is too low for someone like me?

What are your thoughts on this?  I'd love to hear from employees AND managers your opinions!  Thanks!!

THANK YOU everyone!  I think it is great advice the person who said if you question it, it's not appropriate.  So true!  This is kind of what I was afraid of.  A couple of ladies at work told me they thought those dresses would be okay, and I was really surprised.  Of course, they are not the ones who'd be wearing it and they are not supervisors.  Okay, I'm gonna keep that stuff for my days off.  Thanks!