Even on AA metal, TATL flights from LHR have taxes of about $170. For my trip to EUR around Thanks giving, I ended up doing DFW-LHR and CDG-DFW coming back with total taxes of $100/person. I am going in Y and redeemed 20K AAdvantage miles each way. Decided on thanks giving because as someone mentioned earlier, miles required go up to 40K around Christmas.