I was once in the dressing room of a store and a girl told the tailor to hem her pants to an in-between length so she could wear them with flats or heels. I cringed. A frequent fashion error that women (and men) make is wearing pants that are improper lengths. If they are too long it can look messy and ill-fitting while too short can cut off leg lines and look choppy. The correct pant length can be attained by following these three rules.
1) Flats OR heels, not both. The same pair of pants cannot (except cropped, see below) be worn with flats or heels. Have a few pair of pants that are tailored to each height. With heels the hem of the pant should be about half an inch above the ground, or just enough to not drag when you walk. Standard heels are 3.5″ so just take your favorite pair when having your pants hemmed. Flats should also be just high enough to not rub the floor.
2) Cropped/Ankle pants. A pant length that does work well with flats or heels are cropped pants that hit right around the ankle bone. Ankle pants should have a slim leg and be tapered at the ankle otherwise you will end up with capri pants. These look great with heels as they create a long leg line as well as adding a hint of skin. Ankle pants also showcase pretty flats as the pant leg is not covering the shoe.
3) Never Wear Capris-Never. Whoever invented capri pants, both dress and casual, clearly never looked in a mirror. Capri pants cut off around mid-calf and give everyone an awkward leg line. There are more flattering cuts for everyone so even if your office is 100 degrees, resist the temptation and just wear a skirt.