LAS VEGAS (CNN) -- Las Vegas may never be the same now that Britney Spears has started a residency in Nevada's Sin City.
"Britney: Piece of Me" debuted at Planet Hollywood Resort & Casino this weekend, almost 10 years to the day that Spears married a high school friend at a wedding chapel just down the Vegas strip.
Her marriage to Jason Alexander lasted just 55 hours before it was annulled, but Spears' new relationship with Vegas is planned for at least two years. She is reportedly earning $300,000 per show -- $30 million for the 100 shows through 2015.
Spears dances on a 100-foot stage, backed by 14 dancers and one of the world's largest video installations. She enters from a spherical cage that descends from above. Near the end, Spears leaps from a giant tree, flying across the stage on a cable.
While her microphone is live and Spears appears to be singing, much of what the audience hears is from pre-recorded tracks of 21 hits from her pop career.
A live four-piece band plays behind Spears, visible on scaffolding at the rear of the stage. But evidence that much of it is pre-produced comes when Will.i.am appears on video to perform "Scream & Shout" with Spears.
Backing tracks for vocals are not new or unexpected, considering that Spears is running around the stage for most of the 90-minute show.
The 4,600 people attending her opening night Friday seemed willing to suspend any disbelief. They also mouthed the familiar lyrics to "Baby One More Time," "Oops I Did It Again," "Toxic," "Circus," "Womanizer" and "Slave 4 U." She includes songs from her just-released album "Britney Jean."
Unlike most Vegas shows, the theater seats are almost unnecessary. The crowd stood through most of the show as if they were in a nightclub dancing to a DJ.
Planet Hollywood describes the remodeled Axis Theater as "part nightclub and part theater." The VIP section includes bottle service, tables and a dance floor.
Miley Cyrus, Katy Perry, Selena Gomez and Mario Lopez were among Spears' celebrity friends in the VIP section on opening night.
Tickets to the VIP area are in big demand, according to Robin Leach, the "Lifestyles of the Rich and Famous" host who now covers Las Vegas nightlife. One Vegas business owner is negotiating to buy the front-center VIP table for every show, he said.
Spears takes a break after playing the New Year's Eve show, returning on January 29 to begin three shows a week for the next month. Shows are scheduled in four-week segments in April and May and again in August and September.
A younger Las Vegas
Spears' arrival signals another phase in a trend toward a younger Las Vegas that began with nightclubs paying famous DJs big dollars to play electronic dance music.
"The demographic of Vegas has been sliding in the last two years, much younger and the emphasis now is not so much on gaming," said Leach. The younger tourists are shopping, eating, drinking and going to nightclubs, he said.
A fan who was just 6 when Spear's first single -- "Baby One More Time" -- topped the pop charts 15 years ago is now 21 and old enough to fly to Las Vegas and party.
Spears, who turned 32 this month, "is the obvious and natural choice" to take advantage of the younger Vegas because of her fan following," Leach said.
"When you look at the landscape of pop stars, pop princesses, pop queens, there's nobody other than Britney who has the depth of a career and the number of albums," he said. "She has a huge repertoire to go to."
Others will soon follow Spears, Leach predicted. Celine Dion made Las Vegas hot for older superstars when her Caesar's Palace residency began a decade ago, he said.
"Celine brought in Elton (John), Celine brought in Rod Stewart, Celine brought in Shania (Twain)," he said. "Who's Britney going to bring in?"
Bruno Mars, whose first song hit the charts just three years ago, began a mini-residency of headlining eight shows at The Cosmopolitan in Las Vegas Sunday night.