His eventual finesse conducting large groups was no doubt polished while playing piano in jazz big bands led by Charlie Barnet, Tommy Dorsey, and Les Brown. The Brown band became a ticket into another type of show business entirely, one that would prove to have a much larger audience than the experimental bebop sound. Brown went to work for comedian Bob Hope, taking the talented Trenner with him and resulting in engagements as a combination music director, pianist, and arranger for Lena Horne, Nancy Wilson, Jack Jones, Dick Haymes, Ann-Margret, and the Allen television assignment. Outside of network studios, work with vocalists Wilson and Ann-Margret often led to sojourns in Las Vegas.
One of Trenner's greatest assets to performers is apparently his perfectionism; he is often willing to sacrifice great amounts of his own time to make sure a project, or more specifically, one four-bar phrase within that project, is up to snuff. As for jazz, Trenner is not one of those players who let his abilities in this genre go to flab once involved in the glitzy world of Las Vegas shows and network television. His later releases that emphasize straight-ahead jazz or jazz soloing within a song format, such as the 1996 Paul Broadnax date entitled #Here's to Joe, have shown little, if any, degeneration in swing or creative ability. All in all, it could be suggested that Trenner represents an admirable blend of jazz and pop in his work that few performers are able to sustain; brief, and quite enjoyable evidence of this is his piano introduction on the original Nelson Riddle arrangement of Route 66. ~ Eugene Chadbourne, Rovi