I've been listening to The Vitamin String Quartet while writing and sewing lately, they gave me a boost to finish the Upcylced Shoulder Bag one post down. A group of studio musicians from Vitamin Records records pop and rock music using mainly violins and violas, with the occasional cello or guitar to spice things up.
You can purchase their CDs through Barnes and Noble I believe, they can also be found on iTunes or some things on Playlist.com. Here are some links to their YouTube channel where you'll find the most complete collection of their music, here are some of my favorites:
Cover of Oasis's "Wonderwall"
Cover of U2's "Sunday Bloody Sunday"
Bob Dylan's "Lay, Lady, Lay"
No Doubt's "Bathwater"
Muse's "Supermassive Black Hole"
There are plenty of other artists they cover as well; they do some amazing tracks of Nirvana and The Killers.