Sonoma Mountain – a seven mile hike with over 1500 ft of elevation gain. It doesn’t quite reach the top which is outside of the park boundary, but it’s nonetheless a great hike.
The Wolf House – one of the more interesting sites – is the ruins of a 15,000 sqft mansion that Jack London began building in 1910. Before the Londons were able to move in, the house burnt down.
For more details, check out this Norcalhiker blog post on the trip.