Once my foot leaves the elevator in the morning it begins "Good morning sir", starting with the receptionist, if there is a lady sweeping the floor, her too. Walking towards the bank the first guard will say it, followed by one of the guards in the lobby, leaving the bank one of the guards at the guard shack.
When I make it to work the guard at reception will say it, when I exit this area the two guards manning the gate will say it as I approach the main building I will usually pass by one of the cleaning crew who will say it and then finally past the lobby guard.
I don't think I have heard "Good morning sir" so much as since I was a Marine Corps Drill Instructor by the recruits!
Funny thing is when I am with Chris they rarely acknowledge her, only saying good morning or evening to me, whichever the case is. I think it just confuses people to think of a proper greeting when it's a couple. I would think maybe just "Good morning"?.