Among the very best band-within-a-band small-group recordings that Ellington made were those in the early 1940s for RCA Victor, collected on "The Great Ellington Units" (RCA Bluebird), including Billy Strayhorn's harmonically rich ballads "Day Dream" and "Passion Flower," the swinging "Squaty Roo" and the bluesy "Things Ain't What They Used to Be."

The addition of the virtuosic bassist Jimmy Blanton and powerhouse tenor sax man Ben Webster sparked the 1940-42 edition of the Ellington band to new heights, captured on the three-disc, absolutely essential set, "The Blanton-Webster Band" (RCA Bluebird). Included are such canonical recordings as "Jack the Bear," "Ko-Ko," "Concerto for Cootie," "Cotton Tail," "Warm Valley" and the original version of Strayhorn's "Take the 'A' Train."

"Ellington Uptown" (Columbia), recorded in 1951-52, features Ellington's 14-minute "A Tone Parallel to Harlem," arguably his tightest and best extended work or suite. Vocalist Betty Roche, who died in February, lays down an unforgettable boppish scat on "Take the 'A' Train."

Ellington's singular piano "voice" and voicings and deep-in-the-keys touch are often overlooked, but the 1953 album "Piano Reflections" (Capitol) puts them out front in a trio setting of piano, bass and drums. Don't miss the spare, modern "B-Sharp Blues" and the intimate, prayerlike "Reflections in D."

In "Such Sweet Thunder" (Columbia, 1957) – inspired by characters from Shakespeare – Ellington and Strayhorn shine as master dramatists, creating set pieces for the players in the repertory company that was the Ellington band. Johnny Hodges plays Juliet in "Star-Crossed Lovers," Clark Terrycq does a merry Puck in "Up and Down," and Cat Anderson blows his top in a portrait of Hamlet, "Madness in Great Ones."

The 1959 soundtrack recording "Anatomy of a Murder" (Columbia) marks Ellington's greatest writing for movies and one of his best suites. There is a kaleidoscope of moods and tonal colors on such numbers as the languorous "Midnight Indigo," the romantic "Almost Cried" and the haunting "Sunswept Sunday."

The final collaboration between Ellington and Strayhorn, "The Far East Suite" (RCA Bluebird), recorded in 1966, ranks among their best work, highlighted by the lush "Isfahan" and the powerful "Ad Lib on Nippon."

Strayhorn's death in 1967 robbed Ellington of his primary collaborator and a vital source of music for the band. In grief, Ellington recorded a heartfelt tribute album comprised of Strayhorn compositions, "And His Mother Called Him Bill" (RCA Bluebird). Here, the peerless alto saxophonist Hodges makes "Blood Count" into an intense and anguished dirge.

A deeply religious man, Ellington wrote three large-scale religious works. Arguably the best was "The Second Sacred Concert" (Fantasy, 1968) with memorable features for Hodges, Cootie Williams, and the Swedish soprano Alice Babs.

Though Ellington's best writing was instrumental, he also had a number of successes with popular songs. "16 Most Requested Songs" (Legacy) valuably gathers vocal and instrumental versions of his standards, including "Caravan," "Don't Get Around Much Any More" and "Solitude," recorded between 1932 and 1960.

Among Ellington's collaborations with singers, the three-CD set "Ella Fitzgerald Sings the Duke Ellington Songbook" (Verve, 1957) – half of which includes the Ellington orchestra and half a small group – stands out. Listen for the brilliant Strayhorn arrangements of "Day Dream" and "Take the 'A' Train" and a recomposed "Caravan."

The mother of all jazz boxed sets is the 24-disc "The Duke Ellington Centennial Edition: The Complete RCA Victor Recordings, 1927-1973," which BMG Music is releasing on April 27. With a list price of over $400, this set will be beyond the reach of most fans. It set includes a mind-boggling 462 selections with a running time of more than 24 hours. The producers used state-of- the-art techniques to restore the sound, and included all the material on the RCA Victor albums "Beyond Category," "Early Ellington," "The Great Ellington Units," "The Blanton-Webster Band," "The Far East Suite" and "And His Mother Called Him Bill," plus everything else they could find in the company's archives. Among dozens of unissued recordings or alternate takes included here is a heretofore unheard duet by Lena Horne and Billy Strayhorn from the first "sacred concert." The set also includes the second sacred concert, licensed from Fantasy Records, bringing all three Ellington sacred concerts together in one package for the first time. Rounding out this exceptional production is an oversize 128-page book, handsomely designed, richly illustrated and thoroughly annotated.

An inexpensive alternative is "Beyond Category: The Musical Genius of Duke Ellington; His Greatest Victor, Bluebird and RCA Recordings, 1927-67," a 37-track, two-CD set issued by Smithsonian Recordings and BMG. This is the most comprehensive single or double CD available, covering 40 years of his musicmaking. Included are milestones from his early Cotton Club band, the great early 1940s recordings and the late 1960s band, as well as a sample of his small-group recordings. A newly repackaged edition will be in stores later this month. (Full disclosure: I was the producer and annotator of this set.)

While Columbia has not yet released a similar best-of-label anthology, it has grouped some of its choicest material from the 1920s through 1940s onto "Reminiscing in Tempo" (Legacy), and some highlights from 1956-60 onto "The Essential Duke Ellington" (CBS). These two discs from the Columbia archives, together with the "Beyond Category" set from Victor's vaults, provide a historical over view of Ellington better than any other four available discs.

John Edward Hasse is a Smithsonian curator and the author of "Beyond Category: The Life and Genius of Duke Ellington."