Dealing with American Express travel is the same as using any other online travel agency or consolidator. If you have a USA-issued Centurion or Platinum charge card, or a SkyMiles credit card there is no foreign transaction fee. Otherwise, American Express (USA) charges a fee only if the transaction is billed in a foreign currency. If the charge is submitted in US Dollars there will be no fee.
(This does not necessarily mean that the travel agency has converted the transaction to dollars at a favorable rate.)
is it possible to call and/or worth it to try and get it waived? esp as a one time deal. site billed me in GBP and charged me ~2.7% FTF. not a big deal but just goes against my principles, esp cause I booked it here in the US and was expecting the site to bill me in USD.