If you think you have to cross the Atlantic to get a fine port, think again. In sunny California, Prager Winery and Port Works will give you what you crave -- delicious, reasonable and fine port. In addition to several varieties of California port (tawny, white, late bottle vintage and vintage) they also bottle Cabernet Sauvignon and Riesling (Chardonnay is available in some years).
I recommend hitting Prager for a tasting on any visit to Napa Valley. They are open for tastings 7 days a week from 10:30am-4:30pm. The white port is something you will definitely want to indulge in!
Visit their website for information or to shop online.