Originally Posted by
BotB
BTW: I see that we have at least two Ambassadors with us...(one from another forum so we'll hold that against him...) Any tips on how to greet such noble personalities?

It's not just the ambassadors we need to show respect to, but their spouse's also....
Source:
http://www.ediplomat.com/nd/protocol/communicating.htm
Ambassadors are addressed as Mr./Madam Ambassador or Ambassador Jones. Only by special invitation or long friendship should one address an ambassador by first name and then only when not in the public eye. In indirect address, refer to the ambassador as "the ambassador", with his/her spouse as "the ambassador and Mr./Mrs. Jones", or if the ambassador's spouse is a woman who kept her maiden name after marriage, "the ambassador and his wife, Ms. Smith." An ambassador of the United States may continue to be addressed as "Mr./Madam Ambassador" after retirement or after returning from his/her duties abroad. In some French-speaking countries, the wife of the ambassador may be referred to as Madam Ambassador. Therefore, in those countries, refer to a female ambassador by her last name (Ambassador Jones) to avoid confusion and ensure that she receives her due respect.