Plot: The Met's 125th opening-night gala features soprano Renée Fleming in excerpts from three of her favorite operas, Verdi's "La Traviata," Massenet's "Manon" and Strauss' "Capriccio. " Joining her are tenor Ramon Vargas, baritones Thomas Hampson and Dwayne Croft, and bass Robert Lloyd; and she wears costumes designed by John Galliano, Christian Lacroix and Karl Lagerfeld