I'm with bhmadsen: my zigzags go lengthways. This way I can have huge unbroken rows of SAMs to stop the planes.
With lengthway zigzags, to get the most out of your weapons, one of the walls of weapons must be double-thick. I generally make the double-thick wall one of the middle ones, and have mostly SAMs and rockets in it, because they have the range to hit both sides. Slow towers go in the other walls, because they'd be half-wasted in a double-wall.
With lengthway zigzags, there are fewer turns, and so there is less wasted space needing to leave a path for the enemy to get through.