Had the completely opposite experience with AA (Dom Y) recently - SFO to RIC in Dec and JFK to LAX in Jan. Having warned the family of the potential horrors that awaited them flying in the US, we had what felt like two of my best US flying experiences ever (and I usually fly F for business and am QF WP). Checkin in both SFO and JFK were fast, efficient and friendly. The Admirals staff allowed me to guest my family into the lounge (4 of us v. 1 guest entitlement) and the JFK Flagship Lounge was an oasis of calm compared to the QF First lounge in LAX. We flew in Airbus both ways and while, its still Y (actually Main Cabin Extra), the onboard service was excellent.
All that said, wow a 50min wait to checkin, I'd be p*ssed as well.