I'm trying to do a mail merge using my Real Estate Contacts.  There does not appear to be an Envelope Salutation field, although there is a Letter Salutation field.

How can I get  First Name - and - Spouse - Last Name or  First and Last Name AND First and Last Name to appear on an envelope or label?

If you go to the "Address Block" in the merge fields that are options to combine teh FN, LN and Spouse fields.  One thing that you need to make sure is that your mapping of spouse name parts (spouse FN and LN are mapped correctly).