Napa Valley,CA - Many wineries have recently looked to tasting rooms and other direct sales to replace waning restaurant and retail business, but some have depended on direct sales all along. With that in mind, we interviewed the principals from three wine companies that are very successful at direct sales.All are along the popular Highway 29 corridor in Napa Valley, an area hard hit by the economic slowdown because of its predominance of premium wineries. The four wineries profiled (two owned by the same principal), however, are very different.