I have the axiom 50/500 set, my front speakers are about 13ft from where I sit, the rear speakers are on the sides on one line with my seating position, about 6ft off the ground. Pretty much what the booklet that came with the speakers came said.
They are not the same distance, one is about 9ft, the other about 15ft from where I'm at, but it really makes no difference once you set up your system.
But if you're building, I'd definitely add some empty conduits for future upgrades, and I'd also put a strong string into them before closing the walls. Makes pulling cables through at a later date so much easier, especially with corners.
My TV is off center, since there's a fireplace right in the middle, that's why my rear speakers aren't the same distance. But it even says in their booklet that it doesn't matter. As long as you don't go too far back or in front of your seating area and leave enough room to the ceiling for the top speakers.
Oliver