Was lurking on SAH, and saw your Aug plans... I saw a poster recommended the Sea Ranch. It's amazing!! We vacation there every year. Check it out. It's about 5 miles from Gualala, and there's a TON of coastal and wooded hiking both at the Sea Ranch and in Gualala. We'll be headed up there in September of next year. I can't wait!!
Also, the Exploratorium in San Francisco is AMAZING!! They just relocated, and I must say their new set up is fantastic.
If you guys make it to Monterey Bay Aquarium, Dennis the Menace Park is also right there.
In any event, hope you guys enjoy your trip!!