Plug wires have a high resistance. In the neighborhood of thousands or tens of thousands of ohms. This is by design to limit the amount of current used by the spark plugs. Keep in mind that you don't need a lot of current to make a spark. You need high voltage. (Ignition voltage is in the neighborhood of 25kV). And you don't want more current ... your coils would have to be beefier, the wires would have thicker and more expensive. And more current would also turn your plug wires into radio transmitters that would interfere with your radio and electronics, so that would require heavy shielding. Anyway, all this to say that a foot or two is not going to change the resistance significantly as far as the spark is concerned. The spark will punch through it all. (If you really think about it, the voltage is strong enough to spark through air or cracks in insulation). The spark size doesn't matter because you only need to ignite the mixture. It doesn't take much. The spark plug gaps were chosen to accommodate the length of any of the wires.

You're talking about spark plugs that are a matter of inches apart. It's not enough of a difference to affect anything. You would have to have miles of cable before you'd start to notice resistance.