If we enable the use of the Simple Display Name Field, and we dont populate the field for everyone, will exchange default back to the AD Display Name field or will it just show the email address outgoing vs the friendly name for "from"

Hi,

The Advanced tab you are asking about was availble in Exchange 2000/2003 but hasn't been since from Exchange 2007.With Exchange 2013, SimpleDisplayName is configured using Exchange Management Shell (EMS)

Example:
Set-Mailbox ALIAS -SimpleDisplayName $True

From Exchange 2007 Microsoft has introduced the Split AD permissions which means that Exchange can be managed mostly from the EMC .It does not make any trouble in renaming the AD Display Name but  will not be updated in the Exchange end.

Its better you can use this command Set-Mailbox ALIAS -SimpleDisplayName $True  to change the Display name in the exchange part.

Please mark as helpful if you find my contribution useful or as an answer if it does answer your question.That will encourage me - and others - to take time out to help you.
Regards,
Sathish

You can still set the "Simple Display Name" field in Outlook 2010, i'm not certain the option you gave me is what i'm looking for?  I want to be able to show up in address book internall as Duane Haas (Milwaukee), but when sending messages externally, only want to have Duane Haas shown.

Hi,

If you don't configure Simple Display Name, when you sends email to external user, email will appear to come from email address <email address>.

If you have configured Simple Display Name, when you sends email to external user, email will appear to come from Simple Display Name <email address>.

What's more, here is a helpful blog for your reference.

The "not so simple" Simple Display Name

http://blogs.technet.com/b/ehlro/archive/2012/03/26/the-not-so-simple-simple-display-name.aspx

Hope it helps.

Best regards,
Amy

Have a look at this: http://ivasoft.com/selectivesendername2007.shtml