Mauld, sorry but you did get the geography wrong there. Remember that while most of us (including me) have 'mental maps' in which the USA are due west of Europe, and airline route maps can be misleading this way, great circle routes go quite differently and never over iberia.

For example, FRA-EWR flies pretty much over London depending on exact routing of the day. In fact, FRA and BCN are essentially equidistant from EWR, thus a plane flying from FRA to BCN would not be flying toward EWR at all, but in the wrong direction by a full 90 degrees.

Quick doodling at great circle mapper reveals that from a mileage point of view, the two routings are near equivalent. Most of the miles BCN-FRA are compensated by the fact that EWR does not actually lie between BCN and DEN (the planes come in from the northeast).

(edited to add: this overlapped with previous poster, we obviously agree)