Spanish missionaries saw the potential for great wine in Edna Valley (just south of San Luis Obispo) and planted the first wine grapes back in the 19th century. Today, about a dozen mostly mom and pop wineries charm the valley's country backroads. Whet your palette with the white wines of Claiborne & Churchill; their Gewürztraminer is local favorite. Drop into Chamisal Vineyards, the first commercial vineyard planted in Edna Valley. Their small modern tasting room suggests Napa's influence, and their stainless Chardonnay is a crisp and refreshing summer sipper. Located in an old schoolhouse with two bocce courts out back, Baileyana (pictured) is a good place to wind down the day (the Grand Firepeak Cuvee Pinot Noir makes a great bocce partner); their wines are Old World influenced, but their thinking is New School: they have more "Sustainability in Practice" certified acreage than any winery in the state.
The City of San Luis Obispo has an excellent map of the Edna Valley wineries. There is a tasting fee of $5 to $9 at the wineries listed above.