There are several factors one might consider: body shape/size, season, occasion, age and personal preference. Some women are averse to wear dresses as much as a man, some that's all they wear, some it depends.
For myself, being tall, it's difficult. It depends on dress construction. dresses that are seamed/cut midriff are usually too high wasted for me. I have a longer torso, especially compared to someone AFAB at my height. With that in mind, skirts with a long enough top work better. With dresses, a princess seamed sheath, which has no horizontal cut. Whatever the case, 1-2" above the knee at shortest, midi the longest. So 43-50" in length. Think of Capt. Raydor on Major Crimes or some of the women ADA's on law and order. Kate Middleton looks good, but she's a stick and I doubt she buys anything off the rack.