It is hard to find the perfect balance between old and new songs without getting into "wars." That is why our focus HAS to be on the Lord and not on the STYLE of the song. If a song leads us to the King, then it doesn't matter what song it is - the destination is more important. The songs and music are the vehicles that carry our hearts into the presence of the Lord. Church culture, national culture, different generations, etc. all influence what style of vehicle we like...but if we reach the destination of God's presence then we have achieved the primary goal of worship.
It is possible to have authentic worship with contemporary styles of music, ancient hymns...or no music at all. Whatever songs are able to take your congregation on a journey into God's presence are the "right songs" for your congregation. Worship is not about the music - it is about pouring our hearts before the Lord and communing with Him. We should "fight" to have the presence of God - not to have our particular style of music.
Our problem comes when we fall in love with the Lord as we sing various songs. Those songs become our "friends." they take us on the journey into His presence again and again. Subsequent generations come along and their "friends" are different - they discard our old songs and strike up with new songs that are foreign to our ears. That is why younger people need to have RESPECT for older saints and older folks need to be CHAMPIONS for the music and sounds of subsequent generations. Bottom line: focus on the King - the destination of worship...not on the music which is simply a tool to take us to His presence.