Hello,
The drive between the 2 cities is 12 hours, without stops. I've done that drive a couple of times. I-5 of course is the quickest highway to take. And with the timeline you have, taking I-5 is necessary. But it is an interstate freeway and definitely "the beaten path". There's not really many options of places to stop that aren't just another town.
The one place that I can suggest is Ashland, Oregon. Ashland is a college town and the home to the Oregon Shakespeare Festival. Because of the tourism due to the festival, there are some nice places to stay and eat. And the town does have some charm. http://www.osfashland.org/
Have a nice trip!
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