James Taylor has some great acoustic stuff. It's not completely acoustic, but most of the main guitar parts are acoustic. All of his stuff would sound awesome acoustically anyways. I love the song "fire and rain." It's such an amazing song, and he has the absolute best voice ever for the kind of music he plays. I can't get enough of it. You should maybe try out some Cat Stevens stuff. He has a few good acoustic tunes. Also, as funny as their songs may be, check out some Tenacious D stuff maybe. Heck, KG graduated from Julliard at age 13, after majoring in classical guitar. Just about all of their songs have great acoustic parts somewhere.