A floral maxi dress is a timeless choice for a fall wedding guest outfit. Look for a dress with a mix of warm-toned flowers like deep reds, oranges, and yellows to complement the season. The flowing silhouette and long sleeves will keep you comfortable and stylish throughout the event. Pair it with some ankle boots and a leather jacket for a boho-inspired look, or dress it up with heels and delicate jewelry for a more formal affair.