America’s longtime love affair with the music of George Gershwin, one of this country’s favorite composers, is celebrated in high style. In the spirit of the celebration, baritone Robert Sims, who has been hailed by critics for his rich tone, energetic performances, and convincing stage presence and soprano Louise Toppin, who has received critical acclaim for her operatic, orchestral, and oratorio performances, present a sparkling program of the vocal and piano music of Gershwin, complete with classics like “Fascinatin’ Rhythm,” “Lady Be Good,” and “Strike Up the Band.”