I love wearing skirts!
I like to choose age-appropriate skirts (I'm 69), so nothing above the knee. I have skirts from just below the kneecap to ankle length. The longer ones are more appropriate for formal-ish occasions like going to the theatre, and the shorter ones for casual summer wear. When I went for my GCS, I knew I would have to wear a skirt on the way home, but it was winter, so I wore a long skirt for warmth, with knee socks.
Personally, I like swishy, colourful skirts, but I do have a couple of plain pencil skirts. Any wardrobe should have a couple of black skirts: a long one for formal wear (I wore one to a funeral once) and a shorter one for other occasions.
Don't forget that a slip is required unless the skirt is lined. A short one to reduce the transparency of lightweight summer skirts, and a longer one for warmth under longer skirts (such as when I made that winter trip).