There’s a recurrent weekly big market in Dalaran [Legion] every Tuesday, and a similar weekly recurrent event in Booty Bay every Wednesday, and you’ll find people frequently RP’ing there outside of these events as well.
Also there is this awesome 2 days music festival coming up, from Wednesday the 31st of May to Thursday 1st of June, held at Dandred’s Fold, Hillsbrad Foothills, Lordamere Lake, making use of the “Musician” addon, that allows to play precomposed music in game, and which a lot of people playing bard characters have adopted:
Hosted by the AD IC newspaper “The Lion’s Roar”: https://thelionsroar.eu/