Originally Posted by
GinFizz
Unfortunately it can be (and indeed is ) this much ... Putting together your same booking on MatrixITA comes up with a total figure for taxes and surcharges of 1894.65 USD - so the figure your paid is correct.
As mentioned above by
jerry a. laska the YQ surcharge for USA-to-EU/LHR for premium cabin travel is significantly larger than for EU/LHR-to-US. In your case the YQ for MUC-LHR-DEN for booking in J/F is 265 USD, but for the reverse routing (DEN-LHR-MUC) the figure is 700 USD (a difference of 435 USD per person!). If you book this as part of return trip starting in the US, you will be charged the taxes based on the ex-US direction for all legs of the trip
In this case there is a real advantage here and not much downside as far as I can see, to making this as two separate bookings:
SEA-LHR-VIE (you will pay the ex-US surcharges)
MUC-LHR-DEN (you should only pay the ex-EU surcharges)
Agreed, when booking ex-US using Avios it is usually best to book 2 OWs to minimize fuel surcharges. In this case though, I don't believe the OP can do this as the OP mentioned in another thread that he was using a 241.