For a safe semi-casual option, you can always rely on this pairing of a trenchcoat and a white midi skirt.
White Midi Skirt with Trenchcoat Smart Casual Outfits
Combining a trenchcoat with a white midi skirt is an amazing idea for a smart and elegant ensemble. If you're on the fence about how to finish, a pair of grey embellished leather heeled sandals is a smart idea.