Waldorf has larger, better run banquet rooms and have made that something of a specialty. A company can bring in 300 sales people from the midwest and they get wined/dined in reasonable style. Like Vegas, where the guy in the $200 suit from J.C. Penney can walk through the lobby and feel like James Bond, and get treated with the same amount of respect as the playboy son of a Hong Kong banker dropping $3,000 a night for a suite. The Plaza was never any good at that kind of thing. The banquet rooms are smaller and they consider professionally dispensed disdain both a required skill set and a much valued perk.
In regards to parties, NYC has a reputation and proud tradition of including its demi monde at the "free eats." And their quality has deteriorated over the years. As for the legitimate people, well, they have become more corporate conduct themselves like scared and diplomatic rats in very nice clothing. The art world is no better.
Corporate/business parties and those of social climbers are different from N.Y.C. parties of "just friends"...or were.