One of the best parts of living in the San Francisco Bay Area is that you can drive a short distance and be in one of many beautiful spots. On a day in April, I took a drive north up Hwy. 1 through Sonoma County to do some hiking in Gualala Point Regional Park. The park is where the Gualala River meets the Pacific Ocean, so you have an opportunity to hike the trails along the ocean bluffs through Sea Ranch, hike down to the ocean and play with drift wood, or hike a trail that leads you out to the river where you can innertube or swim.
I have a dog, and I like to go adventuring with him, so I chose this specific park to visit because they allow dogs on the trails and beaches. I found the park to be fairly empty for a beautiful Saturday afternoon, and that was nice because some of the trails are a little narrow. I will also mention that it is better to describe the trails as more of "walking" trails rather than "hiking" trails. They are mostly flat and easy to walk along - though you can walk for at least 10 miles if you do all of the loops of the trails round trip.
If you are looking to head to this part of the Bay Area, definitely plan on it being an all day trip. You can stop for lunch in one of the many towns along Hwy. 1, like Bodega Bay or Jenner. The town of Gualala is great for an after hike refreshment, snack or meal, and if you want to make a weekend out of it, I highly recommend renting a house in Sea Ranch.