My favourite skirt length I think is just a bit shorter than knee-length. Midi, the intermediate between mini and maxi, funnily enough, can seem like an awkward length, but it's by no means unwearable.
If you've got a seemingly awkward-lengthed dress you salvaged from the pungent depths of a charity shop, or simply inherited from an older family member, try bringing it up to date with a leather jacket and badass boots like Nancy Z., or introduce a fresh new colour using belts, bags and necklaces like Leeloo P.
I found a lot of pleated chiffon midi skirts in my little hunt for looks. I don't usually wear long skirts or dresses day-to-day, but I love the free, romantic feel it gives me when I do. Sandals, subtly floral top and a satchel, and you're ready to go.