booking an A and C seat has problems on QF who will often manage the booking to put you close together. this can even happen for two passers on the same PNR. my sister and her friend travelled to London, used on line check in and reserved A and C. when they got to the airport they were given boarding passed for B and C. on asking why they were told by check in that their booking had been reviewed, they had seen what they were trying to do (keep middle free) and qf felt that was an unfair use of seating... and so they freed up the window to give to someone else!! (the flight was not packed, but was reasonably full... but there were spare seats dotted around the cabin).
my sister has no status, nor did her friend, so it might be different if two platinums, or golds were to try that trick, but certainly for bronze it failed miserably