In 1975, she became a member of the Bayerische Staatsoper where she caught the attention of Wolfgang Wagner who immediately engaged her for Erda in Richard Wagners Ring des Nibelungen at the Bayreuth Festival 1976 Jahrhundertring (Centenary Ring) in 1976, celebrating the centenary of both the festival and the first performance of the complete cycle, conducted by Pierre Boulez and staged by Patrice Chéreau, recorded and filmed in 1979 and 1980.
Since her concert debut 1964, Wenkel is continuously performing, and she worked with many of the most prominent conductors, e. g. Pierre Boulez, Riccardo Chailly, Colin Davis, Christoph von Dohnányi, Christoph Eschenbach, Bernard Haitink, Marek Janowski, Erich Leinsdorf, Gerd Albrecht, Riccardo Muti, Václav Neumann, Seiji Ozawa, Giuseppe Sinopoli, Gabriel Chmura, Michael Hofstetter, Ulf Schirmer and Klaus Tennstedt.
During the past years, she had several noteworthy role debuts, e. g. Fricka, Waltraute at the Graz Opera, Klytämnestra (Richard Strauss' Elektra) at the Budapest Spring Festival and Freiburg, 2002/2003 the title role in Aribert Reimann's Bernarda Albas Haus in the Swiss First Night at the Bern Opera, and 2012 Filipjewna (Eugen Onegin) at the Staatstheater Saarbrücken.
Hans Werner Henze composed for her the revision of Richard Wagner's Wesendonck Lieder for alto and chamber orchestra, and she performed the premiere under his direction at the Westdeutscher Rundfunk in 1977.
Wenkel is also renowned for giving recitals all over the world, accompanied e. g. by Geoffrey Parsons, Rudolf Jansen, Phillip Moll, Erik Werba, Wilhelm von Grunelius, Cord Garben, Helge Dorsch, Burkhard Schaeffer and Felix-Jany Renz.