Among Charlotte, Tatiana, and Beatrice, it is Miss Casiraghi who attends the most fashion shows if published photos were to be the standard.
I find though that she is the one who is still trying to find her look. Tatiana Sto Domingo has owned the Bohemian chic look with varying success. She is the least beautiful among the three, but she has a very defined identity as far as her fashion choices are concerned.
Beatrice Borromeo is the most statuesque among the three, and she most wisely has used this to her advantage. She can get away wearing perhaps questionable attire -- the sparkling gown that she wore at the wedding dinner would have been disastrous on someone else, but she made it work so good -- because of her figure, poise, and stature. She doesn't come off as cheap or vulgar.
Charlotte has had several hits, especially with her casual/street wear. She is effortless here. But her formal and evening looks are a bit more complicated. It helps that she is gorgeous and is from a family of fashion icons. At this fashion show, she is going for the sultry look with lighter hair, bold red lips and a little black dress. Sure is pretty, but I don't think she is that comfortable. Good that she experiments though.