This dress code is right between formal wedding attire and casual. Since it’s fairly dressy, men can go with or without a tie, and women will not need to sport a maxi-length gown. However, the word “formal” is part of the name, so don’t dress too much on the casual side.
For the guys, this usually means a suit and tie, with or without suspenders, in a dark color for autumn, winter, or evening ceremonies (think dark gray, black, or brown) and lighter shades for spring, summer, and daytime affairs (think powder blue, beige, lavender, and tan).
If you want to shake up a more mundane look, think accessories, accessories, accessories! This is a secret that women have known for years. Try a personality-influenced tie, or a bow tie in an interesting hue with a matching belt or suspenders. Cuff links or tie clips make unique additions to your outfit as well.
Women, for a semi-formal wedding, should try a knee or tea length number with flat, bejeweled sandals. Also, full-length rompers and jumpsuits are certainly a viable alternative.