Offhand, I'd try the RatShack top of line from Monster. It's 12 gauge and 89 or 99 cents per foot.
I wouldn't spend a lot more for surround speakers because there are so many problems with getting serious quality in this installation. My system runs the wires under the house, then back up thru the floor. If you have a dedicated room, and can keep the speaker cables off the floor, then great, maybe a better cable will be significant. But if you have compromised quality already, then what the heck. Maybe if there is a similar cable with a teflon dielectric for about $4 per foot it might have sonic differences. If you're running multichannel SACD with all world class componants, then you need to spend more. But for most class B installations, do the Rat Shack.
