In regards to the guy with kids, I find what usually helps break those type of looks if you just give a friendly smile. Don't worry too much if they don't change. I've had one person literally here in town while in the store cover his kid's eyes who appears to be about 8 years old while in the sight of my person.
I've open carried in Pittsburgh before, last year. I usually went jogging every morning downtown without being bothered. I've only had one encounter with a cop who I believe learned the law, R Pedley.
If you ever find yourself in a situation with an officer, tell him you're going to call one of the lieutenants, which all know open carry is legal and will correct said officers. I can't remember off the top of my head, but after speaking with one of them they will say, "ignorance is no excuse for not knowing the law."