Until personally experience the difference no one agree with the high end/gauge cable funda.. I was one among them until I changed my surround speaker cables.
My denon 3312 was connected with reasonably good cable bought from local shop for last 2 years. As I moved to new house one cable become short and I have ordered C & E 14 AWG 100 feet cable from amazon.
Once I changed I felt that increased sound and clarity (placebo effect) from surround speakers. I have re calibrated with Audussey mike again and found loudness of the rear speaker reduced by -4 .
So now I believe there is something different when using high AWG wires.
The crucial difference, IMHO, is that you need to look at "high end" and "gauge" separately. Basic electrical fundas dictate that a wire, especially for long runs such as 100ft in your case, introduces its own resistance. Call it resistance, or call it current carrying capacity. That is also why 15A wire is thicker than 5A wire. The pipe (wire) has to be literally wider - just like you would for a water pipe.
But, just like a water pipe, there's a threshold. Like you would get benefit from increasing your water pipe from .25" to 1", but if you increase from 1" to a 4" pipe, there might be no point as the water supply itself is not that much.
So going with a higher gauge is definitely a good upgrade (say, from 22awg to 14awg), but only up to a point. I would also say that this upgrade would be especially noticeable in a home theater setup as the power amp section of a multichannel AVR amp is much weaker (per channel) than the power amp section of a stereo amp. So, the reduced resistance of a higher gauge wire, especially for long runs, means that your amp doesn't need to strain as much.
There are a few links online with some very handy charts or thumb rules on what gauge wire you should use for the length of your speaker cable run.
Back to the point, I would say that well constructed, well terminated wire with decent shielding and decent enough gauge is my thumb rule. I am willing to spend money for this level of quality. But "high end" is subjective - and also largely dependent on the quality of other components. Like if I had a Porsche, I would obviously spend more money on my tires as well, even if it is a bit beyond the law of diminishing returns.
The other thing most people neglect is that the nut and terminators are often made of brass. Even some of the high end terminators and binding posts! Which means that your high quality oxygen free copper cable terminates at both ends on a high resistance brass endpoint! So that should be fixed first! (Of course, it is a lot more difficult to do without risking damage)