Hi Mike,
I have facilitated a number of peer groups over the years.  And I agree that they can be useful for an executive.  Most of the issues I've seen addressed were related to business or people strategies.

The challenge with leadership development is that most of us are blind to what's not working.  Therefore, an executive is not likely to bring the issue up to a peer group because they're not even aware of it.
Thanks for your perspectives on this!
Michael