Robert Altman’s swan song is an accomplished ensemble piece that depends so heavily on viewer affection for real-life Midwest bard Garrison Keillor that it stands pat. The premise is simple: A big, bad corporate Texan (Tommy Lee Jones, who appears late) wants to shut down Keillor’s longstanding radio musical burlesque, failing compassion and tradition. Here then is the last night, with the Johnson singers Yolanda (Meryl Streep) and Rhonda (Lily Tomlin) bitching and reminiscing, cowboy troubadours Dusty (Woody Harrelson) and Lefty (John C. Reilly) strumming and punning, and the aloof Keillor orchestrating his sweet brood. Meanwhile, security man Guy Noir (Kevin Kline) spots a mysterious Lady in White (Virginia Madsen) who turns out to be a wannabe guardian angel. It’s all sweet and gracious to a fault, but Altman defers so reverently to Keillor (who wrote the screenplay and plays himself) that the enterprise looks and feels like a documentary ode to the singing little people of the prairie.