Best Source for Ignition 12v in a 97+?

I had to wait for my engine to cool down before I could do a freakin oil change yesterday (stupid ratcheting oil cap!), and decided to wire up my aux lights. The last set of lights I installed had power and ground, but appearantly the laws have changed since then and the KC lights I have now require you to wire up a trigger source so that you can have the aux lights turn off when you switch to low beams. Well I don't want to do that but since any 12v source will work to trigger this "feature" I just need a non-important switched 12v wire.

So what do you guys think? I would prefer the interior but I'm open to the engine bay too. I just don't want to tap into the airbag system, the computer, or the stereo (interference).

Thanks

Best place for a Switched power source is in the Ignition harness under the dash, it's going to be a 12 Gauge wire but I don't remember which color for Switched.
The harness is mess wrapped and will have several 12 gauge wires in it. Don't be afraid to probe the larger wires with a test light as your Airbag wire is small 18 to 16 gauge wire wrapped in a yellow sleeve and is pretty easy to Identify as it's usually stand alone.