Just to throw into the mix, as it seems not to have been covered by others - you said mainly Y fares but as soon as you take a few cheapo Prem Econ fares (on BA or AA), BA treats those very well in terms of TPs (90 per leg), so you'd cut down the number of flights needed quite dramatically for Silver, whilst you wouldn't gain so much collecting on AA. You're also then in the sweet spot (albeit a bit eroded by the new YQ charges) of being able to upgrade those to Club with your Avios.