the beau monde
Collectively, society's most wealthy and fashionable people; the beautiful people. The phrase is French for "fine world." Those parties are exclusively for the beau monde. You wouldn't be invited even as a waiter.
Beau Brummel
A very fashionable man. The name refers to an actual person, George Bryan "Beau" Brummel, who was considered a tastemaker in England's Regency period. That guy's a real Beau Brummel, so I definitely trust his opinion on what I should wear.
Beau Brummel
A male fashion plate. George Bryan Brummel, nicknamed “Beau,” was one of the best-known figures of Regency England of the late 18th to early 19th century. As unofficial fashion advisor to the Prince Regent, later King George IV, Brummel was the arbiter of taste, style, and etiquette; he popularized trousers (instead of knee breeches) with matching coats, as well as cravats that were the forerunners of neckties. The epithet Beau Brummel was applied to any man who was fastidious about his clothing, even if he wasn't a trendsetter.