People here won't tell you this much but 16 gauge is sufficient for most runs, If you actually do the math on it, you really aren't loosing much power. With an 8ohm load, running 100feet, you get 83% of your power to your speaker with 16gauge. With your longest run, 16awg will get 94% of your watts to the speaker, with 12gauge, you get 97%, the difference is 0.17dB, pretty moot by anyones standards.
However, with monoprice's situation, I see no reason to regret going with the bigger wire, you spend a few dollars more. I find it very funny when people begin to get excited about how running 10guage wire makes their speakers noticeably louder for their 6' run when they were using 14 before.