we were recently looking at a very similar situation

we’ll be in Oregon for a couple days before leaving for Europe; there’s an evening nonstop from PDX, but if we want to depart from SEA the best departure is early afternoon, which would mean getting on the road ~630am … the PDX nonstop doesn’t operate on our return date, so we’d be making the PDX-SEA drive in afternoon rush hour after a sunrise departure from Europe and a fairly long domestic leg in Y (we’ll be in PE on the TATL)

what we ultimately decided to do was a cheap award flight SEA-PDX, the evening nonstop, and a connection (with a shorter domestic leg) that gets back to SEA late morning