Shafer Vineyards: Shafer Vineyards is a 32,000-case winery in Napa Valleyâs Stags Leap District managed the father and son team of John and Doug Shafer. The Shafers own and farm 200 acres of vineyards, sources for Shaferâs Cabernet Sauvignon, Chardonnay, Merlot and Sangiovese.