Should we address God by his title or by his proper name?

Most Jews and Christians address God by a title, such as God, Lord, Creator, or Father. However, some people address God using a proper name, such as Jehovah, Yahweh, or Allah. In other contexts, we address those we hold in high esteem by a title, such as Mom, Dad, Doctor, Rabbi, or Pastor. How should we address God?
Update: @ Elizabeth, we call the doctor by his name and title to distinguish him from other doctors. Are you suggesting there are other gods?
Update 2: Doesn't calling God "Jehovah" or "Allah" verbally degrade him to the level of a peer? I certainly never called by dad "Richard," even though that was his name.
Update 3: Interesting ideas about HaShem, literally, "the Name."
27 answers 27