Although the tourist office might maintain that any time of year is the right time for a trip to the Napa Valley, I recommend the spring when the weather is gentle and the crowds minimal; the autumn harvest has its own abundant attractions, but the valley is likely to be mobbed. Before you go, order Napa Valley: From Golden Fields to Purple Harvest , by Denzil Verardo and Jennie Dennis Verardo, from the Napa County Historical Society (707-224-1739). I found it the best history of the valley available. Try to find Robert Louis Stevenson’s The Silverado Squatters at a library; it gives an unparalleled view of Napa life in the late nineteenth century. Those indispensable walking guides can be obtained from most of the valley’s chambers of commerce. For further information, call the California Office of Tourism at 1-800-TO-CALIF.