If you ride up to Avila Beach, you can turn north on See Canyon Rd off of San Luis Bay Road. Nice climb under a canopy of trees. Incline kicks up to 11-12% near the top for a bit. Just before it intersects Prefumo Canyon the pavement ends, so you can make it an up and back, or continue on the dirt for about 1.2 miles where pavement returns. A couple short climbs and you will be at the top with an overlook and a view of Morro Bay/Rock to the Northwest, then a great descent down to Los Osos Valley Rd. near the Madonna Inn. I did this ride from Arroyo Grande in September. FYI I was on my gravel bike with 38mm tires. The dirt bit would probably be doable on 28mm. Here is my Strava of it:
https://www.strava.com/activities/1863541376
You can also ride up to Lopez Lake to the NE of AG.