In fact I think you might find consistency and less change makes people more comfortable, young as well as old, as long as they feel welcome in your church. Build a Christian community and good, lively liturgy will happen - or it has here, anyway. Coming from a protestant background I am cautious about going too far down the road of 'getting bums on pews' which so many people seem to focus on. My Catholic parish has seen a massive revival in attendance in the last 2 years, through the efforts of the pastor. I believe however what has made the most difference here is not the liturgy itself or the music style, etc.
People socialise together, they become friends, they go to church with their friends.
You can't please everyone liturgically and churches perhaps need to stop trying and focus more on community and enthusiasm instead of music style. In fact I think you might find consistency and less change makes people more comfortable, young as well as old, as long as they feel welcome in your church.