A couple from Marina del Rey were among the five people who died Friday when a light plane crashed into an apartment building in the Fairfax district, relatives said Monday. Tony Vinatieri, 42, and Bonnie Vinatieri, 41, had joined the flight to Sun Valley, Idaho, because the pilot, Jeffrey T. Siegel, was a contractor who wanted to show them houses he had built there, John Vinatieri of Napa said.