The ferry trip is amazing! Enjoy the sites and any ranger programs that they might have scheduled.

I think you should add at least a day to your trip from SLC to Bellingham. First, because you're not allowing anytime at all for sightseeing. Second, because Umatilla to Bellingham is over 300 miles and you have to drive through the dreaded "I-5 Parking Lot" to get there. Seriously, traffic from Olympia to Everett can sometimes be a nightmare and take far longer than you anticipate. If you cross over to Seattle from Eastern WA via Snoqualmie Pass on I-90, you will be able to miss some of that traffic by taking I-405 North to where it meets up again with Seattle but, still, traffic through here can be a nightmare most anytime of day.

When are you going? At this time of year, it's conceivable that you will still have slow-downs on Snoqualmie Pass. Here's a link to the DOT page that can give you current pass conditions. You might want to keep an eye on this before you leave, in addition to watching weather reports, to see if you should come up from the south via Portland due to weather conditions. And, unfortunately, this winter a few avalanches have been bad enough to entirely close the pass a couple of times. That's rare but something to consider.

If you go up through Portland, you're traveling almost 450 miles on that leg of your trip and, because of the potential traffic slow-downs, it could easily take well over 8 hours to make that trip. Or not...because it all depends on how bottle-necked that traffic gets.

Anyway, if I were you, I''d want to be much closer to Bellingham on the morning your ferry sails because, if you miss it, aren't you toast? Don't you have to pay for the passage anyway? I don't think they give refunds easily. I guess that's why I'm trying to give you complete info so you can weigh the risks of potentially missing your boarding time.