Memorial Hospital is city owned and only has signs that only prohibit OC.
Penrose Hospital has a silhouette of a gun with a circle-slash. I interpreted that to mean no OC.
I had a dispute with a hospice nurse and went to their headquarters at the St, Francis medical building. They had big sign with all of the "will be prosecuted" BS. I don't think that there is anything that they "could" prosecute you for, except maybe third degree criminal trespass, which is a class 1 petty offense. IANAL, but I believe that a defense to this offense, would be that you rectified the situation by leaving immediately when asked. I mean I don't read every sign that I pass, I just didn't notice it.
University Hospital in Denver has signage prohibiting weapons, but the Colorado Supreme Court recently ruled that they were preempted by state law, so I just figured Screw 'em.
Pike Peak Mental Health Center has a sign that says if you are caught with a weapon police will be notified.
My conclusion? Go ahead and CC and no one will be the wiser. If by some slim chance someone catches you, its not likely that you would be prosecuted. If you were, there is a good chance that you would be acquitted, and if by some stroke of lottery bad luck you ended up convicted, it is still a very minor offense.