I know you already have a Rarity ball gown pic.



https://derpibooru.org/925214?q=artist%3Atoughset



But think you can make one more seductive like the Princesses' pic



https://derpibooru.org/936916?q=artist%3Atoughset



Also it would be really cool to see the Dazzlings dressed up for the ball, not to mention Sunset Shimmer, Sci-Twi and the main Crystal Prep girls.