One of the most relaxing tastings I have been to was the one at Plumpjack. A lot of folks know Plumpjack because of their city restaurants (featuring Plumpjack wine) or the Squaw Valley Inn. The winery is in Oakville, CA and is a perfect spot to stop off for a glass or 2 of Chardonnay, Cabernet, Syrah or Merlot.
The tasting room is open 10am-4pm every day except Thanksgiving, Christmas, New Year's and Easter. On Christmas Eve & New Year's Eve, the tasting room in only open for half of a day (call ahead).
Tasting notes are available online if you want to prep for your visit. you can't order online, but you can get an order form there and fax/mail it. www.plumpjack.com