On a recent flight from JFK-SFO, I was (initially) travelling in First Class on a three-class aircraft, and so was able to use the Flagship Check-in at JFK. As I was connecting from a BA flight and used the AirTrain between terminals, the entrance was right by where the lifts from the AirTrain walkway comes out. The sign is not totally obvious:

To obtain access you have to show your boarding pass and the agent at the entrance checks a list before admission. Once inside the area is bright and quiet, with just one agent working:

After checking my boarding pass and confirming that I had no bags, she directed me out of the exit (you can see in the distance). This deposits you at the TSAPre queue, but as I am not allowed to use it (Foreign National), the TSA agent had to summon an AA employee. This employee assisted me with my bags and slipped me to the front of the queue. As the line is the non-priority line there were some strange looks, but the AA employee was helpful and assisted me getting ready for Security. For example, I learned that I did not need to take out the iPad any more.

So a good, if not great, experience. The negative was simply the Pre/Non-Priority line handling which is beyond AA’s control.