Surf City Cyclery in HB is a great shop with excellent employees/mechanics. Their turn around is faster than anybody in OC. Santiago Oaks will be close to your work, and also check out Laguna Coast Wilderness/El Moro State Park, although you'll need a guide to find most of the good stuff. In south OC, the Weedpatch (San Clemente Singletracks) and Las Ramblas (Dana Point) are also really fun on a SS, but a guide would be helpful the first time to figure out good routes and to find the best trails.
Because we like the taste of freedom; because we like the smell of danger. ~ E. Abbey