KW on the left. Jay-Z also wore jeans

This was a young crowd, mostly 20-somethings and 30-somethings. The look: Urban casual. There were a lot of micro-minis and high heels, a lot of baggy pants and jeans. Jay-Z and West each wore a black jersey with "JZ" on the right sleeve, KW on the left. Jay-Z also wore jeans, boots and his ever-present New York Yankees baseball cap. West wore leather pants and sneakers. Stage setting: This show was visually spectacular. There was a main, T-shaped stage where both entertainers performed together, and also two cube-shaped mini stages, one at each end of the arena, that rose and lowered at various points during the show. West and Jay-Z performed separately on these cubes, which showed various images (a snarling pitbull, a swimming shark) at different points of the show. Fireballs the size of car tires shot from the floor toward the ceiling during some performances. Two large video screens behind the main stage showed appropriate images during the performances; a virtually non-stop laser light show added to the oomph factor. Venue:Philips Arena downtown seats 21,000 for concerts. The facility, which opened in September 1999, is the home of the NBA's Atlanta Hawks. Energized crowd: This was a very high energy crowd. Many of them remained standing -- and swaying and dancing and singing -- for the entire 2 1/2-hour show. At one point, as Jay-Z and West performed N---as in Paris from their new hit CD, "Watch the Throne," West exhorted the audience to "Bounce! Bounce!" The resulting stomping had Philips Arena rocking and shaking in a way that it hasn't for the Hawks in a long time. On-Stage chemistry: Both artists were on-stage -- first on those cubes, then on the main stage -- for the opening segment of the show, performing songs from their new CD -- Welcome to the Jungle and Otis, among them. Then they each performed a number of their own hits, sometimes singly, sometimes together. The audience roared when they heard favorites like West's Monster, Power, Touch the Sky and Gold Digger, and Jay-Z's Dirt Off Your Shoulder, Big Pimpin, H to the Izzo and 99 Problems. "They've each had so many hits, I was interested to see how they would go back and forth," said Tony Wheeler, 36, a Greenville, S.C. radio personality in town for the concert. "I thought they did a really nice job with that. You noticed how they would each do their own thing on some songs, then blend it back together?" Coolest, non-gang-related hand sign: Jay-Z repeatedly told the crowd to "put your diamonds up," and they repeatedly complied, pressing their index fingers and thumbs together. ATL connection: Although West was raised in Chicago, he was born in Atlanta. To the crowd's delight, he and Jay-Z played up the Dirty South connection several times. Best Sing-Along: When Jay-Z performed his and Alicia Keys' 2009 Grammy-winning hit, Empire State of Mind, he urged the audience to sing the refrain. They did so to great effect, and at the end of the song, Jay-Z removed his Yankees cap and waved it at the audience. Onstage quotable: During one short break between songs, Jay-Z draped an arm across West's shoulders and said: "Atlanta, you are now looking at black excellence at its finest. Make some … noise!" Moving Performance: When West sang his hit, Runaway, about a man who always finds fault with the women in his life, he seemed to really pour himself into the song, and appeared to be in tears at the end of it.