The Coast Starlight finally seems to be running regularly--no more 10-12 hour delays. At least, let's hope so. Usually, the Starlight is pretty punctual southbound--though it can be an hour or so late. That should not affect connections from the Builder. But, suppose there is a derailment or something on the Builder line; that could create a significant delay. You might want to have a backup plan to stay overnight in Portland just in case. North/eastbound, I would ALWAYS plan to stay over night in Portland (or Seattle).
This time of year, it is getting tricky in terms of hour much daylight you will have passing though Glacier, which would be about 7pm. You may get the sunet and its colors on the surrounding mountains, perhaps silhouettes of mountains, and such. On a night like tonight, you might have the full moon, which will help with illuminting some of the landscapes, and perhaps the rivers.