I've always mentally associated Vanessa Carlton and Avril Lavigne. They both came onto the scene at around the same time, and both seemed to have songs geared primarily toward teenagers. While Avril's music was for the Bad Kids, though, Vanessa's was for the shy girls who write poetry and dream of Prince Charming sweeping them off their feet. Or at least that's what the record companies who signed them were hoping; I'm not sure how well that worked out in actual practice. Anyway, Vanessa's lyrics struck me as rather trite teenage poetry stuff, and her vocals were kind of...exaggeratedly sweet, or something. She was a talented pianist, though (she apparently started at the age of two), and her instrumental parts were genuinely enjoyable, so I couldn't help but kind of like songs like "A Thousand Miles" even though I'd heard the same basic sentiments expressed in a million other songs. Vanessa is presumably still recording, although I get the impression that she's one of those artists who will only be recognized by the general public for her early work.
And since it's apparently Doppelgänger Week, I might as well mention that I've always pretty much figured Vanessa and Michelle Branch were the same person.
The thing is, however, that while I know I've heard some of Michelle's music, I can't for the life of me remember any of it. The conspiracy-loving part of my brain thinks that Michelle was an alter-ego that Vanessa created as an outlet for her more boring music, as well as to play a different instrument (guitar instead of piano) and pose for Maxim.