I have publicly vaped in at least three county courthouses (not courtrooms, I'm not that stupid), a federal building, and a county jail with no one saying a single discouraging word to me.
But use some common sense and stealth vape if you think there will be a problem. Blowing thick clouds of fog around non smokers is stupid, discourteous and give a bad name to the vaping community.
This is the key. When the public knows what you are doing they are very supportive but if they don't know what you are doing they get nervous.