Yes, this is really a gray area. I guess I'll just remove from my pocket, my Spyderco "Police" model with it's 4 1/4 inch blade especially when going in/through Denver.
I live out in the "sticks" and my big Spyderco is in constant use. I also volunteer to frequently drive a van load of disabled Vets to the VA in Albuquerque for their various appointments and if the van is ever in an accident, I like the capability of being able to quickly cut the required seat belts from my passengers. I really feel that a larger blade may be more efficient in cutting any jammed belts. That's my reason for using the big blade knife and I sure as hell have no criminal intent with my wearing it. Of course ALL knives along with any type of dangerous weapon is strictly forbidden in the VA Hospital so it remains in the parked and locked van.