Don't overspend on fancy speaker wire but be sure to use the correct gauge(thickness) for your application. The length of the wire and impedance of the speaker are both factors to consider when determining the minimum gauge that should be used. The longer the length, the thicker the gauge you should use. Also, the lower the impedance of the speaker, the thicker the gauge.
For 8 ohm speakers, 16 gauge is fine for runs up to 25-30 feet. 14 gauge for runs up to 40-60 feet. 12 gauge for runs up to 100 feet.
For 4 ohm speakers, I would limit 16 gauge to runs around 10-15 feet. 14 gauge for runs up to 25-35 feet. 12 gauge for runs up to 40-60 feet. 10 gauge for runs of 60-80ft
Now, these aren't "hard and fast" rules. So if you are running a little longer than the above recommendations I wouldn't worry about it. As long as you are "in the ballpark" with the above suggestions that really is fine.
Power Sound Audio