Seattle to San Francisco

Everyone should drive the Oregon Coast Southbound at least once in their lives! Absolutely beautiful IMO, and lots to do along the way! But, it is a lot longer than I-5 for sure and really requires many stops along the way to enjoy it. The road is good all the way down for most any set up (you didn't say what you were driving). If you don't have the time, I would not use it simply as an alternate route. You'll be tempted too many times to stop and check out the points of interest and towns along the way which would frustrate your schedule? Realistically, you would have to allow an extra 6 hrs driving time if you just go straight thru cutting over at Longview Wa and coming back onto I-5 at Eugene OR. To do it right, you'd probably want to take about 6 days!