So - shorts are not just hot & sexy. They can be smart looking as well. In a proper organization, most probably they won't allow staffs to wear short pants to work. But in those more creative lines, the marketing and advertising people, they can be creative in how to present themselves as well!
When you're wearing it more formally, go with a little more formal top. Don't have to be pure black and white or grey, add in some colours to show y our personality as well. As long as it's simple plain colour, you'll still look professional :)
To add in feminine touch, you can try with the lace short pants. Simple and elegant.
P.S: a small reminder - if you are wearing a lace pants, try not to pair with lace tops (unless it's a set piece) as that will distract the focus of your pants. Something plain and simple on top will be nice and sweet! :)