Josie..
EXCELLENT post! Exactly what I was hoping for, only much better than I expected!

I would add that the same thing is true of lyrics as is true of standup comedy... people enjoy topics with which they identify. Standup comics find success with stories that make the audience think "yeahhh... me too!"

stories that have a common human element of pleasure, fear, hope, faith, passion, excitement etc are all good.

Likewise, recurring themes like holidays, weddings, funerals, seasonal changes, mood changes... ANYTHING that recurs will make your lyrics applicable again every time the cycle recurs.

For example, every halloween you still hear MONSTER MASH even though its a corny little song that wore out long ago... but once a year, every year, it works!