New York City Ballet’s four-week fall season, which ends on Sunday, has belonged primarily to its music director, Andrew Litton. New last year, he has now committed himself to conducting the company’s central repertory of ballets by George Balanchine: familiar scores have returned with new immediacy. Details of orchestral phrasing have registered keenly, with a wealth of color; he gives many scores a strong pulse. For years, the best orchestral playing in American ballet has belonged outside New York; but this may well now be changing.

The dancers haven’t always looked relaxed at his first accounts of these ballets — but it’s worth returning to see later performances. On Wednesday, this was so with the season’s final performance of its oldest ballet, George Balanchine’s “Serenade,” in a richly colorful performance led onstage by Sara Mearns, Tiler Peck and Jared Angle.

Other problems, however, diminished this season’s “Serenade.” Its women have been given new, problematic versions of the old Karinska costumes, with skirts of a stiffer fabric than before. And whereas the two beige front panels used to be so subtly hued as to melt into the surrounding blue, now they’re lemony. Until these skirts can be softened or changed, the sweep of this ballet is inhibited.

Mr. Litton sprinkled magic elsewhere, even with Hershy Kay’s score for “Western Symphony” (1954). Before this Wednesday’s performance, I’d been thinking that we all needed a long break from this war horse. Thanks to Mr. Litton’s alchemy, however, Wednesday’s rendition had real élan and zippiness. Some of the ballet’s jokes have grown stale, but not its steps. Dancers at both corps and principal levels were frolicking deliciously with them.