We like to put a removable mounting bar under our dashes. We mount everything electronic to it and have connectors so that we can wire it out of the car and put it in, and remove it if we have to. Nothing is wired so that you would have to cut anything to remove any one component.
We have two main weatherpaks on either side of the firewall. All the left side wiring exits on the left, and the right on the right. This way, NO wires cross over on the car at all. This means you can hide all the wiring easy with no wires running accross the chassis or floor. Normally the accuair is mounted down with the valve blocks etc, we hid it up here.
All the wiring is clean and grouped once its all plugged in.
Our ac lines get treated to the same wire covering as our harnesses.