LENOX -- Part revival meeting, part gathering of faithful kindred spirits, Garrison Keillor's annual public-radio broadcast of "A Prairie Home Companion" rolled into Tanglewood on Saturday evening.
Many in the throng of about 9,000 fans stayed for what turned out to be a marathon, two-hour singalong with the host after the "on the air" sign went dark shortly before 8.
As has been his wont in recent broadcast seasons, Keillor, now a rather decent singer in his own right, put the emphasis on down-home Americana "roots" music in one of his strongest outings here since his show's tradition of spending the last Saturday in June at Tanglewood began in 1998.
The guest performers were a formidable group on Saturday, led by folk hero Arlo Guthrie -- "we always like to give some local talent a chance," said Keillor by way of introduction. Guthrie, who heads to Oklahoma shortly to celebrate the centenary of Woody Guthrie's birth, was in his element, offering selections from his famous dad's 2,000-strong songbook ("Pretty Boy Floyd," "Philadelphia Lawyer" and "Oklahoma Hills") as well as a bang-up arrangement of Arlo's biggest hit, "City of New Orleans," written by obscure singer-songwriter Steve Goodman in 1972.
Guthrie also proved to be a decent comic actor in a "Guy Noir, Private Eye Skit" portraying "Mr. Debris," a wacky yokel whose circus-like "Twisted Corners" farmstead wreaks havoc with a Tanglewood concert with his choir of singing turkeys and chickens.
Other standout musical turns came from Catskills resident Heather Masse, the New England Conservatory-trained jazz vocalist who crosses over into multiple styles, including crooning, swooning ballads such as her standout "Lazy Afternoon." No wonder she's a "PHC" regular (often with the Canadian band "The Wailin' Jennys").
The close-harmonizing DiGiallonardo Sisters (Daniela, Nadia and Christine) from Brooklyn effectively channeled the Andrews Sisters, and also performed authentic, yet individualized covers of the Chiffons' "One Fine Day" and Lennon-McCartney's "Because."
Sound-effects master Fred Newman had an especially challenging starring role in multiple Tanglewood-oriented skits with actors Tim Russell and Sue Scott, while and music director Richard Dworsky impressed once again with his chameleon-like ability to adopt every musical style in the book,abetted by guitarist Pat Donohue and colleagues -- especially Richard Kriehn, a classical violinist equally adept with bluegrass fiddling and even the mandolin.
Prowling the stage like a ringmaster at an old-time vaudeville show, rearranging segments on the fly with impeccable timing, Keillor was at the top of his game, with his alter-ego "Sara Bellum" augmented these days by two real writers.
Tellingly, with Keillor a month away from turning 70, his unusually dark-toned "News from Lake Wobegon" monologue dwelt uncomfortably on mortality as he conjured up the grim tale of a grandma who drops dead suddenly and is barely missed.
But the good news for his devoted three million or so listeners is that he has put aside thoughts of retirement, having told the Sioux City (Iowa) Journal last winter that "the show is going well. I love doing it. Why quit?"
With all the fun he and his merry band have on stage, on air and on tour, not to mention the cottage industry he has created, the answer must be -- why, indeed.