I like the EB westbound for the Cascade crossing, and the CS southbound for views of Mount Rainier (as well as some coastal sections,at least for now--there is a track realignment under construction that will eliminate a very scenic stretch).
Which Silver is better for scenery? The morning Cascades between Seattle and Vancouver traverse the scenic coastal base of Chuckanut Mountain in the daylight even in the wintertime. One of the world's greatest views is of Orcas Island from a train!
May I ask which part of the Coast Starlight specifically is poised to be eliminated, due to a proposed track realignment? I really fear I'll never get to ride the Coast Starlight, before that realignment occurs.

And ETA, is it this Port Defiance segment of the CS route through Tacoma per the Washington state DOT website? Which is at:
https://www.wsdot.wa.gov/projects/rail/pnwrc_ptdefiance/
I'd really love to do a Southwest Chief westbound/Coast Starlight northbound/Empire Builder eastbound trip as I live in Chicago, but I bet the cost of that would probably be expensive. Would be great to do such a trip in its entirety(and f it if it's so expensive, whole cost might be worth it), since I have a relative out in the LA area. And as I've always wanted to ride on both the Empire Builder(had only ridden that route via the Hiawatha to Milwaukee) and the Coast Starlight!