The Seattle Symphony has announced that its 2009-10 season will open on September 12 with piano concertos of Rachmaninoff and Tchaikovsky, featuring pianist John Lill, at a silver anniversary gala honoring Gerard Schwarz’s 25th anniversary as the orchestra’s music director. Highlights of the orchestra’s upcoming season include a Bernstein celebration to include the Symphony No. 2 (“Age of Anxiety”) and Serenade; the world premiere of Golijov’s Fantasia sobre La Pasión según Marcos (“Fantasy on St. Mark Passion”) for two pianos, with Marielle and Katia Lebèque; and a centennial tribute to Samuel Barber. Mark Morris will conduct the orchestra and choreograph his dance troupe in May “Basically Baroque” concerts at the Paramount Theatre. Guest artists making their debuts include violinists Isabelle Faust and Henning Kraggerud, cellist Daniel Müller-Schott, and pianists Gabriela Montero, Dejan Lazic, and Ingrid Fliter; recitalists will include soprano Renée Fleming, violinists Joshua Bell and Julia Fischer, and pianists Jeremy Denk and Jean-Yves Thibaudet.