<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by headinclouds:
Will the BA staff tell me to use the AA lounge since I am departing on AA?</font>
You should be entitled to access to any OW lounge, at your own discretion (I've done a similar thing at DFW). Whether you'll meet with a resistance from BA lounge folks at IAD, I don't know, but if I were you, I'd insist on my rights.