If I may throw in my penny's worth, and Yarg, please feel free to whack me on the head and correct me if I'm saying crap, but there's a trick that my boss / BFF (a much better guitarist himself than I could ever be) told me about having learned about in SOS: Of course, panning guitars to 9-10 on the L and 2-3 on the right works. But also when you double the guitar tracks, change something on the dubbed guitar's overall sound, eq, a different distortion, or just a nice crisp crunch to cut through the mix and give a more complex flavor to the final mixed sound. Throw even a subtle almost subliminal acoustic in nashville tuning buried in there. I believe that's one of Steven Wilson's go-to's.
OK... now let me run for cover, see if I can duck the whack from Yarg and Ramo!