I don't fly AA international F that often but over 25 years of flying AA, I don't ever recall the captain coming out to introduce themselves - why would they? Why would I want them to? Clearly, they do have "more important things to worry about".
Was the PDB actually (a) champagne and (b) served in a glass? Or was it some unidentified sparkling wine served in plastic? Nothing screams "THIS IS NOT FIRST CLASS" more than those dreadful plastic glasses AA insists on using.
We're flying LAX-MEL next month in QF J. We could have taken the LAX-SYD AA flight and then used SWUs to upgrade - obviously subject to availability but it's a RTW ticket that's changeable at will and we're time-rich these days (if cash-poor...) so probably not too impossible to find a day with upgrade space. We opted not to and to stick to QF J direct to MEL. From your description - and certainly from JDiver's comments - it sounds like we made the right call. Very disappointing that AA continued its usual mediocre service standards on this brand-new high-profile route.
I believe (my memory is a little hazy on this) the PDB was served in a stemmed glass (not plastic). I had water and am unable to comment on the bubbly stuff. I thought the service in F was great and certainly not mediocre. I am unable to comment on the service in J.