Jim Elbrecht wrote:

One of the options the salesman offered was tempered glass. My
first instinct was 'sure, why not?' -- but the more I think about it,
I have trouble justifying the extra $2-300 for 3 windows.

These are second floor windows- not in a high wind area, though there
are trees nearby. They are not within range of any golf balls,
baseballs, or other missiles. The windows that are there now have
survived 110+ years without shattering. [likely the original windows
as all the panes have bubbles and imperfections]

So is there something else I'm missing that makes tempered a
worthwhile investment?

Tempered glass is usually only required where there is a high probability of
someone slipping or falling nearby and putting a head, arm or other body part
through the glass. In most residental applications not on a golf course, that
means in the bathroom or in sliding doors. Can't imagine why you'd want the
expense in a standard window. Your local code may vary.