I find the most meaningful songs are those that are based on a single, central image or theme. It seems many songs we hear today are too disconnected and thereby lack impact,while others are simply fluff. I've always been impressed by the images created by writers like Townes van Zandt(eg.one of my favourites, "Tecumseh Valley").
I was thinking the other day that now matter how close we may be to others we are essentially alone. This brought out the following verse, which in turn brought out an , as yet unfinished, song:

Though we may stand together
It seems solitude's what we know best
From our thoughts on the wind we are tethered
To the feelings alone in our breast

To me it's often these simple themes that lead to "good songs". I hope we keep this discussion going a while longer. So far I've enjoyed all you comments, and am looking forward to more.

Dave T