I love her. She's not 100% perfect, but honestly, I think I outdid myself on this one. Holy.
Her "holiday" is the International Circus Festival. It's on the Monaco's official calendar... they don't really do holidays in Monaco apparently. The only holiday they do have as an "official" holiday is their heritage day of sorts which constantly changed throughout history to be on the day of the ruling prince's patron saint's feast, and then Prince Albert decided to keep it on his father's day, Prince Reiner III... but there's no real "traditional" other than a military presentation and the prince waving at his people.