Just getting back to this.......

Thanks all for your comments & advice ^

I have some doubts creeping in about booking on ba.com, I think I might play it safe & go with aa.com. I know I'll lose the option of selecting EI flights for the feeders, but I can live with that if my seating assignments work better, along with API etc.

If I do book with aa.com, I presume that there's no issue with selecting seats on the TATL legs, but how would it work for the BA operated CE legs between DUB & LHR, can those seats be selected on the AA site ?

Also, in relation to not being guaranteed AA's new J product, the LAX route seems to be one operated by the 777W. I know that equipment changes can happen, but generally how reliable is the 777W on the LHR-LAX route ??

Thanks again for all your help, I need to get this nailed down pretty quick as the sale ends on Tuesday, so your advice has been of great help ^