Britney Spears ended her Las Vegas residency after a highly-successful four-year run. Over the weekend, the pop star returned to Vegas for the first time since that final show, but this time she wasn't under her father's thumb.On March 5, Britney and her fiance Sam Asghari headed to Sin City to celebrate his 28th birthday."There was no drama," a source told Page Six. "She got picked up in a Rolls Royce, [was driven] to the hotel and had a great time."After checking into the Presidential Suite at the Crockfords tower of the newly-opened Resorts World, Sam and Britney reportedly had a couple's massage.