Q. Whom do we address in prayer?
A. We directly address God the Father in the name of God the Son by the empowering of God the Spirit.
Most instances of prayer in the Scriptures are directly addressed to God the Father (most notably, the prayer the Lord taught His disciples in Matthew 6 and Luke 11, see also John 16:23). It seems that this should be the normative pattern for our prayers. All prayer is Trinitarian, however, in that the entire Trinity is involved in each of our prayers, and each member of the Godhead is equally God and equally worthy of our worship (Ephesians 5:20, 6:18). It is, therefore, acceptable to pray to the Son and/or the Spirit at times when it seems appropriate.