In the winter, Armação dos Búzios is a quiet beach resort made famous by Brigitte Bardot (one of the pictures below is her statue). Apparently it is shoulder-to-shoulder packed in the summer. They call it the Saint-Tropez of South America. Heavily visited by South Americans (including plenty of Brazilians); very few from the USA. If you don't know some Portuguese, you’ll have to learn quickly—few people speak any English.
Shops generally don't open until 3 p. m., and things don't get really active until well after dark.
Beautiful scenery, excellent food, lots of bikini shops.