I lived in PO for the past 4 years and used to do the PO to Seattle commute, so I think I can guesstimate what the commute time might be. You'd be going in the opposite direction of the greatest concentration of traffic, but still across the Narrows bridge (which is now a toll bridge with a currently $3 one-way toll, see link at
WSDOT - SR 16, Tacoma Narrows Bridge Project). On a good day (no accidents or other problems), you could probably make it into PO from UP in about 45 minutes. With traffic, however, your commute could be significantly extended. For some reason, people slow down on the bridge -- maybe this will change with the opening of the 2nd span, but I doubt it -- and it can be quite aggravating to be stuck behind an inexplicably pokey driver doing 10 or 15 mph under the speed limit. While the 2nd span of the Narrows was being built, people would slow
way down to watch the construction, and it made me want to tear my hair out (reference the opening scene in "Office Space"). It is rare to actually do the speed limit over the bridge.
Hope you find this helpful. Good luck to you.