THEATER MAY be the most evanescent of the arts -- once the cast has taken its final bow, nothing's left but the memory. In the case of the musical theater and the occasional play, the "original cast album" is the only thing that survives to document the experience, aside from perhaps a ticket stub or a dog-eared playbill. The cast album has become popular as a souvenir of the experience for those who've seen a show and as a surrogate for those who haven't. But a cast album has to be more than just setting the cast in front of a tape recorder and letting them go; it has to work on its own as a record, which often means restructuring the songs and the sound in the studio.

City of Angels (Columbia). This spoof/celebration of film noir set in 1940s Los Angeles was the big winner at the Tony Awards. And thanks to some creative editing and production, Cy Coleman's period-evocative tunes and David Zippel's playful lyrics can stand alone when separated from Larry Gelbart's sly script and Robin Wagner's neato color-vs.-black-and-white setting. Standout tracks include Randy Graff smoldering through the torcher "With Every Breath I Take"; "What You Don't Know About Women," a cleverly staged and snappily sung duet between two gal Friday characters featuring Graff and Kay McLelland; and "You're Nothing Without Me," in which pulp-fictional gumshoe James Naughton and his author, Gregg Edelman, wax antagonistic and metaphysical.

Gypsy (Elektra Nonesuch). This recording is one of those "you had to be there" situations: Tony winner Tyne Daly takes on the literally breathtaking role of Mama Rose, that ultimate stage mother -- it's a wonder she makes it through eight shows a week. Daly's squarely at the center of half of the numbers in this faithful recording of the handsome and much-honored revival. But you can't watch her, and the lack of visual distraction makes it impossible to overlook Daly's seriously strained, flawed singing. Everyone else shines, though, and thanks to the storage capacity available on CD and cassette, this is the most complete recording of this essential score to date.

Jerome Robbins' Broadway (RCA Victor). The album is a handsomely packaged, double-disc cash-in on the prodigious director/choreographer's splendid "greatest hits" retrospective. But the recording is kind of beside the point, as the show is about the dances. Paul Gemignani's orchestrations of familiar music -- the ballet from "West Side Story," the "Sunrise, Sunset" number from "Fiddler on the Roof," "I'm Flying" from "Peter Pan" and a few rarities -- are certainly enjoyable, and the album functions nicely enough as an anthology of some of the American musical theater's brightest moments. But you can find better, more definitive and historic performances elsewhere.

Meet Me in St. Louis (DRG). They sure don't make 'em like this anymore. They don't even revive 'em like this. "Meet Me in St. Louis" turns around the tradition of turning Broadway hits into movies. South African producer-director Louis Burke got the idea of crafting a stage version of the 1944 movie. So original songwriters Hugh Martin and Ralph Blane were commissioned to come up with 10 new songs; the late Hugh Wheeler, a Sondheim collaborator, created a new libretto. A big part of the project was a search for bright unknown voices for the vintage and vintage-sounding songs, and when newcomer Donna Kane goes up against the memory of Judy Garland singing "The Boy Next Door" and "The Trolley Song," she fares quite well. The album captures the archaic charms of the lavish production (you'll have to buy a ticket to see the onstage ice-skating) and its all but lost American optimism.

Aspects of Love (Polydor). Having toyed with cats and choo-choos and phantoms in his past few shows, Andrew Lloyd Webber sat down to address humans and grown-up themes in "Aspects of Love," a quasi-operetta based on David Garnett's 1955 novel. The story pits youthful passion against the wisdom of age in a series of romantic triangles and other, less tidy, geometric arrangements. But Lloyd Webber's melodies are less tunes than piano primer exercises, and the banal lyrics of Don Black and Charles Hart reduce emotional complexities to pop cliches. Before you get to the endlessly repeated Big Song ("Love, love changes everything/Days are longer, words mean more/Love, love changes everything/Pain is deeper than before . . .") you slog through miles of tedious exposition and recitative, much of it a wan retread of Lloyd Webber's weak "Song and Dance," and still you don't come away with any insight you couldn't get from a New Kids on the Block hit.

Miss Saigon (Geffen). This is an armchair preview of the new blockbuster from the "Les Mise'rables" creative team, Alain Boublil and Claude-Michel Schonberg, already a hit in London. And as in the case of "Les Miz," another Cameron Mackintosh-produced blockbuster, "Miss Saigon" is already raking in the bucks on T-shirts, mugs and other merchandising; the handsomely packaged, lushly recorded London cast album should be one of the biggest selling souvenirs. A reworking of the "Madame Butterfly" plot -- replacing the lovers with a Vietnamese prostitute and her callow G.I. suitor -- "Miss Saigon" shares with "Les Miz" a sprawling scope, spectacular staging (sets include the sleazy sex bars of Bangkok, a spectacularly vulgar vision of the American dream, and a balletic reenactment of the fall of Saigon, complete with a helicopter flying in to lift out embassy personnel), and musical tendencies split between the anthemic and bathetic. Boublil's lyrics to such songs as "If You Want to Die in Bed" and "Let Me See His Western Nose" live up to their awkward titles -- they sound like the translated French they are. But partner Schonberg's got a knack for yanking heartstrings and unstopping tear ducts, and it's his music that puts this really big show across.

Jekyll and Hyde (DRG). Given the frightening success of "The Phantom of the Opera," it was only a matter of time before others began scavenging the library stacks for horror classics to musicalize. Leslie Bricuse and Frank Wildhorn settled on the Robert Louis Stevenson tale of "Dr. Jekyll and Mr. Hyde," which has a meatier subtext than "Phantom." Bricuse, who wrote "Stop the World -- I Want to Get Off," and Wildhorn, who has written hits for Whitney Houston, among others, come up with a dozen so-so songs (memorable music, sappy lyrics) on this pre-production showcase. They were lucky enough to snag Colm "Les Miz" Wilkinson to sing the dual role of the schizy doctor -- he makes even the lamest lines sound like winners. Wilkinson's heroic tones are nicely paired with Linda Eder's lush sound -- she plays Jekyll's bewildered girlfriend, and oddly enough, it's she who gets to sing the song called "No One Knows Who I Am."

King (Decca). Last but not least, here's the cast album from a musical that may never be seen -- on these shores, at least. The musical, a meditation on the life and martyrdom of Dr. Martin Luther King Jr., closed two weekends ago on a West End stage, after a severely curtailed run. The musical has a strong pedigree, with music by Richard Blackford, lyrics by poet Maya Angelou and Alastair Beaton, and an adaptation by playwright Lonnie Elder III. But the show is at odds with itself -- as exemplified by the earthquakes that take place on the set, and a stylistic schism within the cast. King is played by Metropolitan Opera baritone Simon Estes, whose mighty voice is commanding in song, but comically wooden in speech. Coretta is sung by Cynthia Haymon, and is just as operatically saintly. But the rest of the cast have pop-soul theater voices, a` la "Dreamgirls," and the show becomes a tug of war between opera and popera that is never satisfactorily settled. But in spite of its many failings as theater, "King" packs an emotional wallop. Someone should snap up the rights to the story and title, and start all over again -- this is a story that deserves to be sung on American stages.