Functional bikes. Not Porn not Anti

So...

    I'm getting an art studio at the end of the summer and need a bike that'll allow me to transport materials and supplies to and from. It's not going to be a long commute but will be about ten miles.
    I've been looking into a Surly Karate Monkey. I like the idea of the simplicity of a singlespeed but would it make a lot more sense to have gears? I've also read somewhere that disc brakes and racks don't work together on the Surly. I'd want to put drops on it and then occasionally be able to go out on some weekend rides doing a bit of light bike packing.

Is this doable or should I be looking at other options?