Accuse Rod Stewart of what you like--through the years he's been calleda philanderer, a has-been, a pageant-ish progenitor of puff rock--but as he has consistently proved with his Great American Songbook series, the concept of dignity is not lost on him. There is a time, after all, for leaping across stages in leopard-print spandex while shamelessly parading an unparalleled gift for scratchy-voiced seduction, and he is past it. Past his prime is another thing. On this fourth installation of the Clive Davis-produced series, Stewart again makes excellent use of his rolodex: Diana Ross, whose affection for this material comes through as convincingly as her spike-haired partner's, cuddles up for opener "I've Got a Crush On You," Chaka Khan packs her bags but not her mighty vocals for "You Send Me," and Sir Elton shelves the recent balladeer's instincts for a rip-roaring run through "Makin' Whoopee." A handful of marquee instrumentalists also returned Rod's calls-- Dave Koz blows sax on "Nevertheless," and trumpeters Chris Botti and Roy Hargrove turn up the heat on "I Wish You Love" and "My One and Only Love" respectively. As on earlier discs, though, it's when Rod rules the spotlight alone that he can be most compelling: Cue up "My Funny Valentine" in the right frame of mind and you may never need to hear it sung by another. Retiring the satin shirts in favor of this material was the smartest move Stewart ever made.