As live performers, Robin and Linda Williams are second to none and are at home on whatever stage they find themselves — be it a tiny coffee house or bar, or a large, storied concert hall or festival. Closing in on a five-decade career, credits include 24 personal recordings, thousands of concerts on three continents, a Robert Altman-directed movie, hundreds of performances on NPR's "A Prairie Home Companion" and other radio and television shows.