I'm not sure how far I can go without being too digitally involved.
If this is a straight scan, it explains it. They always come out too flat. If you print it in darkroom, you are likely to find it's ok.
What I think you need is more contrast. I loaded it into NX2 and slid the black point to the top edge of the histogram. The image improved significantly. So in darkroom term, bump up the contrast one to 1 1/2 grade and expose so you get a full range of tones.
To me, your biggest problems are faces. They are gray. They need to be much lighter and brighter.
Here's how I would print it.