I5 route is about 800 miles, coastal route is closer to 1000 miles. Lots of little towns you can stop by for the night, sort of Carmel without the money if you know what I mean: Mendocino/Fort Bragg, Eureka, etc etc. Scenery is stunning, better than the drive south. It's foggy and wet sometimes (Eureka is the rainiest town in California, more Blackpool than Bakersfield). The little towns, well, it depends on what you mean by 'lots to do', but those more suited to tourists tend to have lots of B&Bs and nice restaurants which aren't quite of the quality you might find in SF or Seattle, but nice. You'd be on the road 5/6 hours a day, so in the end not sure you'd be looking for much more than a relaxing pit stop along the road, the beauty of the drive itself is really the selling point for something like this.