Thanks for the quick answer.  I have to say, that seems like a pretty brain-dead requirement.  What is so hard about puting a button on my account settings page, next to the alternate email address, that says 'Make this address my primary'?  That seems pretty straight forward to me.  I'm guessing that Google's convoluted accounts machinery is placing moronic restrictions on what should be a simple task.

Unfortunately this scenario won't work for me at this time.  I'm using a Google Voice utility that's only able to log into a gmail or google apps domain (I assume that too is related to Google's overly complex accounts architecture).  So I can't delete gmail, at least for now.  I may eventually try to re-jigger my whole account setup.  But for now it appears I'm stuck not getting notified about G+ posts (Hello!  Google! are you hearing that?  I'm not using G+ because you don't notify me of posts at an email address i actually use!).  So Facebook it is then...

Again, thanks :)