"I am AA gold and will be AA gold next year. That means I can use the J check-in and get elite seating in coach.
I have a Qantas Club membership that runs until 02/05. That gets me into AA, BA, US, and of course QF lounges.
Will BA silver get me anything over what I already get through AA gold and the Qantas Club?"
Well, you would get access to all OW lounges when travelling with any OW carrier, so your lounge access would extend to include CX, AY et al. e.g. at the moment, if you were to take a flight with CX you would have no lounge access rights at T3 whereas as BA Silver you would get access to the AA lounge ( which your QF club card wouldnt )
Supposedly, your chance of getting an operational upgrade may be increased by being OW Sapphire rather than ruby.
Dave