I second that - we go to Martinborough a couple times a year & tasted at Haythornthwaite last time. We now call it "that winery with the beautiful Gewurtzes''. Lovely.
Another winery close to Haythornthwaite is Vynfields - their wine is decent (maybe not spectacular), but we really enjoyed lunch in their beautiful garden - their fresh bread/homemade soup was soooo good. Best bread I have had in ages.
You'll have a wonderful time; it's so pretty and relaxing but there's good hiking, too if you're feeling more energetic.