During the Jazz Age, there were more than a few artistic go-betweens who cut paths from the club floor to the concert hall, carrying aspects of each tradition hither and yon. But no composer had as much respect in both scenes as Gershwin, whose vernacular-inflected symphonic works like “Rhapsody in Blue” have been lodestars for generations of conductors. (Bernstein cut a great “American in Paris” with the New York Philharmonic in his youth; Ludovic Morlot has followed that example early in his time with the Seattle Symphony.) Likewise, Gershwin's supposedly pop-side songs for the stage—such as tunes from Porgy and Bess—have spent decades in the jazz-standard songbook before coming back to the classical world as piano miniatures deserving of recitalists' attention.