Arlington Park, with shade, water, restrooms, and tables, is a good start and end for walks that mix city and country, with great views. The map shows one possibility.
From spring-fed ponds near the center of the park, follow the creeklet south to exit, and carefully cross Arlington, at Arlington and Brewster. Follow paved paths and steps along the partially-buried creek. (At King, an alternate continues down to Shevlin Place, with a larger but less scenic loop possible through the grassy area under power lines.)
The route shown here follows King and King Court to one of six entrances to the Hillside Natural Area. Follow this service road north, above a former quarry and across the top of the 90-acre mosaic of grassland and oak forest. Bay views and spring wildflowers are spectacular. (Branching downhill on sometimes- steep roads would provide a larger loop; map and info on the Hillside Natural Area at http://www.fivecreeks.org/projects/hillside_natural_area/.)
At the four-way intersection, the route shown here goes right to Regency Court near Kent. (Alternatively, continue straight to the end of Regency Court, and return on Regency, passing twisted oak forests and a lovely creek.)
To explore Camp Herms as well, follow Kent east to Contra Costa, Contra Costa south to Buckingham, and then Buckingham to Arlington. (A shorter route back to Arlington Park would follow Brewster.)
At Arlington, Buckingham changes names to Rifle Range. (Ardent bicyclists or long-distance hikers can labor up Rifle Range and then steeply downhill into Wildcat Canyon Road.) For the walk shown here, jog south and cross Arlington to Thors Bay Road, edging the north end of Arlington Park.
Take Thors Bay a short distance uphill to the entrance to the Boy Scouts’ Camp Herms, another old quarry. Follow the service road/trail uphill through redwoods to a great view east to Wildcat Canyon, and loop back down past cabins and the disused, WPA-built rock swimming pool.
Due to poison oak, I don’t recommend cross-countrying down into Arlington Park, although this is sometimes possible. Instead, return to Thors Bay and re-enter the park from there.