Actually, you probably wouldn't even be IN most of those buildings.
If a property owner wants to put up signs saying "TRAINED, LAW-ABIDING CONCEALED-CARRY PERMIT HOLDERS NOT WELCOME HERE," then screw 'em. They're not worthy of your business anyway.
And they can deal later on with the massive civil liability lawsuits when some maniac takes 'em up on the welcome mat, and comes in their cute little "gun-free" zone and murders and maims their customers.
I posted on this very point over at NewsBusters. The first such shooting in a “gun-free zone” could possibly have been a “gimme”. But, once the owners of such gun-free zones saw what can happen, they should have taken those signs down. I hope that the survivors of such shootings start filing law suits, perhaps even class-action suits against shopping malls, banks, universities, schools, and such places that have taken away the right of self-defense from the people. If they post such a sign, they have assumed the duty to defend the people inside. If they are negligent in that duty, then they should be sued into bankruptcy. All those signs do is proclaim “Victims Here!”