What is the best way to drive from Sea Tac to Bear Ntn, Vancouver Island?

I would also recommend Google maps, with traffic being so various its really just a gamble. Good luck in your travels

It always depends on the traffic, I would recommend you use Google maps and plot your trip out from where you're at to where you want to go. It will give you real time traffic updates and allow you to best choose the route for your situation. As traffic situations change Google maps will update and give you recommendations on how you can change your route to make it best.