Do the Santa Barbara Channel Islands count? I'm always shocked by how many people from California have never been out there. I live in Minnesota, but I've been out tons of times. I love all five islands that are part of the National Park. Santa Cruz is probably my favorite for hikes, especially as a day trip, but the outer islands are gorgeous as well, in their own bleak ways. 

Irish Hills is a great hike in SLO. Also a good resource is hikespeak.com.