Rock and Roll Hall of Famer Bonnie Raitt has been palling around with Harlem-bred bluesman Taj Mahal since the '60s, bonding through a mutual love of roots music. But this is the pair's first tour together; they'll coheadline under the name BonTaj Roulet and will donate a portion of the proceeds to a variety of charitable organizations. Mahal's tunes, which fold African and Latin influences into the blues, should be a lively counterpart to Raitt's sensual melodies and expressive slide guitar — both will play individual sets and then come together onstage for a buoyant finale. At 59, Raitt can still belt out her sentimental ballads ("I Can't Make You Love Me") and upbeat sing-alongs ("Something to Talk About") as beautifully as she's been doing for 40 years. It's like she's often told her audiences — the blues never go out of style.