Swenson has appeared on many opera stages, including the Opéra National de Paris, the Royal Opera House at Covent Garden, the Metropolitan Opera, the Berlin State Opera, the Grand Théâtre de Genève, the Hamburg State Opera, the Bavarian State Opera and the Chicago Lyric Opera. Roles she has played include Liù in Turandot, Rosina in The Barber of Seville, the Four Heroines in The Tales of Hoffmann, Elvira in I Puritani, Zerbinetta in Ariadne auf Naxos, Gilda in Rigoletto, Juliette in Roméo et Juliette and Giulietta in I Capuleti e i Montecchi, Violetta in La traviata, Lucia in Lucia di Lammermoor, Adina in L'elisir d'amore, Marguerite in Faust, the Countess in The Marriage of Figaro, and Rodelinda in Rodelinda. Swenson received an honorary doctorate degree in April 2006 from the San Francisco Conservatory of Music, where she has taught master classes. In March 2007, she returned to the stage of the Metropolitan Opera, singing the role of Marguerite in Faust. The March 17 performance was broadcast internationally. On April 21, 2007, she performed the role of Cleopatra in Handel's Giulio Cesare at the Met. However, Swenson was unhappy with Metropolitan's General Manager Peter Gelb's apparent decision not to use her as much as his predecessor Joseph Volpe had. Swensons stated: "It’s hurtful. I’m a New Yorker. I’ve sung here for many, many years. I’ve had great success. I’ve never let them down. It’s so stressful to get up onstage and realize that the top guy doesn’t like you, and there’s nothing I can do about it. Nothing." In May 2007 she again sang Marguerite at the Cincinnati Opera, and sang the role of Hannah Glawari in the Dallas Opera's The Merry Widow in November–December 2007 opposite Rod Gilfry. In June 2008 she sang Ginevra in Handel's Ariodante opposite mezzo Susan Graham at the San Francisco Opera, a production that marked Swenson's 25th anniversary with the company. Also in 2008, she sang Violetta at the Metropolitan Opera. On July 6, 2008, Swenson was awarded the San Francisco Opera Medal, the company's highest artistic honor. According to David Gockley, General Director of the San Francisco Opera, "Swenson has had a long and illustrious history with this Company, and we are thrilled to honor her significant contributions to San Francisco Opera and the performing arts in this way." She returned to the Met in 2010 as Musetta in La bohème.