Daytime hangouts...
Well, depends really
Bora Bora is probably the busiest place, on the biggest beach - Playa D'en Bossa
As for time to arrive, i personally like the late afternoon and early evening when the suns gone down... But for day time? hmmm, anytime mate, its always buzzing around there...
Otherwise, any of the beaches around the island. Salinas is cool, and you can catch Jon Sa Trinxa playing downtempo stuff, and there are some serrrrrious women there, strutting there stuff...
ermm, otherwise, just grab a a hire car and explore, theres more to ibiza than the clubbing...