I was recently waitlisted on several American Setctors - they seem to have precious few A seats to anywhere domestic US anymore - but when AA came to ticket it, their fares desk spoke to inventory control and cleared all the sectors I needed.

The odd thing was YVR-DFW where I was waitlisted for weeks and weeks, cleared on ticketing, then the plane left with 4 empty seats, but AA think I was on an upgrade and so have only given me the basic miles!