Indigo Girls & Jewel & Sarah McLachlan

While they came into prominence as part of the late-'80s folky singer/songwriter revival, the Indigo Girls had staying power where other artists from the same era quickly faded. Their two-women-with-guitars formula may not have seemed very revolutionary on paper, but the combination of two distinct personalities and songwriting styles provided tension and an interesting balance. Emily Saliers, hailing from the more traditional Joni Mitchell school, boasted a gentler sound, was more complex musically, and leaned toward the abstract and spiritual. Meanwhile, Amy Ray drew heavily...