By Debbie Hall It is a milestone celebration of Las Vegas' creative scene as The Composers Showcase marks 20 years with a special anniversary gala at The Smith Center for the Performing Arts on April 29. Keith Thompson More than just a concert, the evening is designed as a full-scale artistic experience—two and a half hours of all-original music performed by a cross-section of Las Vegas’ most accomplished creators alongside special guest artists from across the country. At th