Ok, so somehow when looking for more info I stumbled across this on the Hilton site:
http://hhonors.hilton.com/en/hhonors...rs_terms.jhtml
It's a comprehensive guide to booking Partner Awards - the real 'how to.'
Of note:
For airline awards the seats are pulled from the following fare classes:
Air Canada - W (Award Ticket)
Alaska - Award Ticket
America West - G
American - Award Ticket
British Airways - Award Ticket
CO - Award Ticket
Delta - ?
Hawaiian - P/Q/Y
Mexicana - U
Midwest - Award Ticket
South African Airways - U
Southwest - Award Ticket
United - V
US Airways - Award Ticket