With a carnival-themed extravaganza, China concluded its debut as Olympic host Sunday after 16 days of nearly flawless logistics and superlative athletic achievement that coexisted awkwardly with the government's wariness of dissent and free speech. To a large extent, the emergent superpower got what it had sought from the Games: a dominant effort by its athletes to top the gold-medal standings for the first time and almost glitch-free organizing that showcased world-class arenas and cheerful volunteers for the largest-ever peaceful influx of foreign visitors. As a bonus, two athletes gave what might be among the greatest performances in Olympic history - Michael Phelps with his eight gold medals in swimming, Jamaica's ebullient Usain Bolt with three golds and three world records in the sprints.