Here are two of the rules we live by:
--Never break a gun law, because it's usually a felony.
--Never expose ourselves to danger because some {deleted} posted a sign that does not constitute a "gun law," because that's just silly.
The Christiana Mall, and the local movie theater, are public places, and we believe that we are not denied the RKBA there under Delaware and local law.
Our lawyer agrees. As near as we can determine, it is legal to carry in those places.
{Deleted} them if they don't like it.
We choose to enter the mall through entrances that do not have the "Code of Conduct" policy, but that's just for more convenient parking [ahem].
Costco, OTOH, is not a public place. Although they have a national "No Firearms" policy, there is no sign on their Delaware warehouse.
The day they put one up, I shall return my membership card and demand a refund... and explain why, in person, at the membership desk.