You get AA Flagship lounge whether upgraded or paid FC. In addition, BA serves super-premium spirits in F (e.g. Johnnie Walker Blue Label and Camus XO cognac, Perrier Jouet champagne). The BA lounge at LAX serves premium spirits and snacks while the F lounge at Heathrow mirrors what's available in flight. However, notably missing on AA and BA is the formerly requisite caviar service! However, are these perqs worth the premium price? You decide. You can get discounted J cabin on BA for as little as $3,500 on the LAX - LHR non-stop whereas F cabin is over $15K. No discounts. On the other hand, it's only 50K miles extra per tkt for F vs. J on BA and 35K more on AA if using award tkts.