Perhaps a way to avoid the LHR/LGW dance is to use Iberia, an AA partner, for LAX/JFK/MAD/VCE. There are also IB options through MIA and MEX. Coming back from DBV via MAD requires an overnight there, but there are worse things. This return could be interesting: ZAG/BUD/LHR/LAX using a combination of Malev, BA and AA or even more exotic: TGD (Podgorica, Montenegro, about a 100Euro car ride from DBV) to BUD on Malev, then BA to LHR & AA to LAX. Among the downsides are that you would have AA reward reservations scratching their heads. In any event start working on it 320 days from your scheduled return home and good luck.