The Paro tsechu (spring festival celebrating the advent of Guru Padmasambhava into Bhutan) is a must see. It is considered to be one of the best tsechus in all of Bhutan, and is held near the Paro Dzong at spring every year, including day long festivities and masked dances over 5 days.
Also, while in Bhutan, try to gather (or buy) Bhutanese currency (ngultrum), exquiaitely beautiful and depicting Buddhist sacred symbols






