Moderator: American AAdvantage, Signatures
Join Date: Jan 2008
Location: London, England
Programs: UA 1K, Hilton Diamond, IHG Diamond Ambassador, National Exec, AA EXP Emeritus
Posts: 9,795
MCE is free for oneworld Sapphires.
You can add your trusted traveller number to your AA booking for PreCheck.
You're way better off booking on AA's site, as booking through BA will give you BA marketed codeshares on the US domestic connections that book into business fares not first, screwing you out of points/miles. I don't see any reason not to book with AA if you're flying AA.