You will find a lot of people here who live lifestyles similar to yours, much more so than in SoCal. (I've lived in Santa Cruz for 12 years, but grew up in SoCal). It's like a whole other state down there!
Overall this is a very liberal and casual town. People go grocery shopping in their pajamas and no one thinks twice about it. There are ALL kinds of people here. I love it so much. Outdoor activities are endless. Plus, it's beautiful; we really do live in paradise! The surf is good (but the water is COLD, full suits needed all year). We also have the redwood forest, nearby lakes, streams, and mountains. San Francisco is an easy day trip too.
I don't know a lot about the unschooling community, but the homeschool community is large and active (much of it Christian). There are so many homeschool options. There is a lot of great food here too. We have good restaurants and an abundance of fresh local produce all year. There are tons of CSAs and farmers markets. But, there are cons to living here too.
The cost of living is extremely high, one of the highest in the country. Also this is a tourist destination, and we get the crowds and traffic that go along with it. Luckily they are usually gone by the time our best weather rolls around in the Fall (summers are cold and grey). It's a college town, which could be good or bad depending on how you look at it (and on if your next door neighbors like to party!). Crime rates are surprisingly high. There is a fair amount of gang activity, and the general attitude of tolerance has lead to a thriving heroin trade and transient population.
Be careful about what neighborhood you live in, each one is really different. I'd suggest renting for a while so that you can get a feel for things before buying. Or, if you know of any specific areas you'd want to live, I could tell you all about them!
You can also get a good sense of the type of community SC is by browsing through the different groups on Meetup.com. There are lot's of Yoga, vegan and other similar interest groups. It's not quite as crunchy as someplace like Oregon, but for California this is pretty close!