EastBay-
Did you do this run this past Saturday? I was on the 2130 SFO-LAX on AA and could have got you into the AC. Let me know if you have any upcoming weekend flights the next month (PM me). It's pretty small compared to UA, but very nice staff across the board, and usually pretty quiet that time of night.
I'm not a fan of AA 757's, as they're the only seat in the entire fleet that for some reason makes my knees hurt after a few hours. I just can't get comfortable in that seat. Sadly, we're seeing more of them on transcons (they run SJC-JFK, as well as DFW-SMF).
We just had a discussion on the AA board about checking in for return flights. The synopsis is that you can do this ahead of time only if the routing is different coming back. If it sees the same segment (say, a MIA-SFO), it won't let you check in until after you arrive (if you had an AC membership you could do it there on one of the PC's in MIA, or just as the AC counter). I've done 3 Omaha trips this month and was able to print all my passes on two of those because of a different routing coming home. On the one trip where I had ORD-OMA, followed by OMA-ORD, it would not let me check in for the return flights.
Trust you're doing well, even though I haven't seen you for a while. Glad to see you're back in the air