So often a visitor evaluates a prospective church by the younger generation present. I am not so sure that young people are the best determinate of spiritual life in a church. Do they have it? I sure hope so! But the trend among the younger generation as a whole is that they are transitory and noncommittal. Therefore, one may join a church because of a large group in that particular age group, but the majority of the group could be gone the next year.
I would postulate that a better determinate of spiritual vitality in a given congregation is in the old people. Is the older generation full of joy and growing? Are they interested in encouraging and edifying the saints? Do they love and admonish others? Are they willing to do their part in the Body of Christ? If you find a church where the older generation loves Christ and seeks to know Him, latch on!