First of all, filter down your music collection. Takes a while but i am sure you will manage with only 11MB

i know you meant GB. Just, too easy, y'know?
I would really need to know your music tastes. But at the moment (and many moments) i am listening to John Mayer, Jason Mraz. Mainstreamish? nah, not compared to the drivvel we have to hear on radio day in day out.
Other suggestions, though not vocal, still are great and interesting pieces of musicianship you could get into:
Thomas Leeb - Great percussive acoustic guitar player, get his album Desert Pirate, or maybe its Grooveyard.. i think its the first one.
Derek Trucks - his band are brilliant, though his music may not be down your ally, his bands vocalist is a bit breathy for some, but their songs are brilliant and if you're into sweet rock blues guitar, this is your destiny on a disc.
Chris Geehan & Dan Byrne McCullough - Iji Soundtrack - i hear good things from these guys, they're not superb and are novices at the craft but definetely some good rocking and ambient works from them, they haven't released the soundtrack yet, but i would imagine in a few weeks it'll be annouced for official circulation.
Other than that, if you don't already listen to In Flames, i suggest their earlier albums, including Trigger.
Pagan's Mind is always a good call for well written AND brilliantly epic heavy metal /prog rock pieces, a taste of Dream Theatre and Symphony X can be found in their music along with their own brilliant sound. I think they're the end result that every band that is compared to them, is looking for.
I'm heading down a power metal route here so i won't go further as i don't think you like power metal? i'm not sure though.. ill try touch on another band i remember from ages ago but never got into, but they were good.. ahmm, their name is..
The Birthday Massacre, don't know if they're great but i found a few of their songs are nice, kinda dark electro rock. It was refreshing, though it has been years since i listened to them.
I'm grasping at straws here because i don't think you'll be into the other music i listen to, but for a great GREAT AMAZING piano piece, 45 minutes long, get Keith Jarrett - Vienna Part 1. The first 10 minutes are so brilliant, and the other 35 are just as great, so yeah.. nice reflective beautiful piano piece for you there.
This should get the ball rolling, somebody else want to input?