This is how I think it should be done and how my wife addresses me.

My Wife uses my first name during normal times and while in company however I do insist she uses my full name and not the shortened version as  I think that is a good way of her showing respect for me.  Also when we are with friends & family this does not cause her any undue embarrassment.

When she displeases me and needs correction it is then that she must call me Sir and this has to continue for the full duration of the punishment, failure to do so will only lead to an extra spanking as I see it as a lack of respect.

During our play time such as evenings away in  a hotel that are our special treat time, she will call me Master once we are on our own.