The FC fast track at SEA in the morning is a piece of cake. NEVER a wait. Also SEA has free wi-fi throughout the airport if that matters.

For me it would be a no-brainer: two nights with consecutive red-eyes v. a night in a bed? Plus, in August DFW's location in the middle of thunderstorm alley can and does make for interesting days - more than once I've stood looking out the window as the ground crews drop everything and scurry for shelter as the lightning flashes and the thunder booms, leaving planes half-fueled, luggage in carts getting well irrigated, and thousands of passengers wondering if they're going to get to Paris or Peoria that day. Feh.

The seats on the 763s are a little narrower than on the 777; however IMO the cabin is more user-friendly (2-2-2 seating instead of 2-3-2) and the service is usually closer to F levels than J.

Again IMO hoping for a J > F op-up on DFW-CDG is a waste of neurons. Way, way too many EXPs in the DFW area with SWUs to burn on longhauls.

As for the 500 mi. difference, I'd bet money that can be recouped with ease in Europe or Europe-Asia in your itinerary.