Recommendation for in-wall speaker cable

I am just completing a renovation on my house. Before the contractor closes the walls in my family room I am having him install two in-ceiling speakers. I'll post in the speakers forum to get speaker recommendations, but I'm leaning towards Definitive Technologies UIW RCS II.

The tricky part is cable. The ceiling is about 11' and the cable needs to drop down to the next floor down where the components will be (plus a lateral run to one side of the room) -- all told about 30'. It is an exterior wall but the cable will be on the inside of the insulation. The vertical run down the inside of the wall will cross (at a 90 degree angle) a metal conduit containing household power cable.

Any recommendations on a specific cable or the characteristics of an appropriate cable?

Thanks a lot!