Alaska still hasn’t opened up SEA to LHR for next summer and I’m guessing it won’t show up until they finalize the leased Heathrow slots from AA. They’ve got the SEA KEF and SEA FCO trees live now, but nothing yet for London which makes planning a Europe trip kinda annoying.
Also yeah… the old money plus miles option is gone. At this point the only workaround is still buying one way with miles and the other with cash unless you’ve got the full pile of miles for a round trip.