We got home yesterday from a week-long visit to Northern California which included 2+ days in the Anderson Valley. Thanks to everyone who posted their recommendations. I want to second most of them, especially Esterlina. What an amazing experience - just the two of us with friendly tasting room person Amy pouring as much as we wanted of their lovely wines as we sat on the deck and enjoyed their gorgeous view. We were there just before lunchtime, so wound up bringing in the cheese and apples we had in the car and enjoying them with the wines.
Other favorites were Navarro and Husch for everyday wines. Both offer a wide variety at moderate prices and had wonderful picnic areas. Besides their wines, Navarro offers Gewurztraminer and Pinot Noir grape juices which were absolutely delicious, also a Verjus of Chardonnay.
For higher-end (but worth it) wines, I want to recommend Lazy Creek. The maps say they're appointment only, but we were told to drive by and "if the gate's open, they're open". We did, drove in and were greeted by three friendly dogs - always a good sign. Like so many wineries in the area, their specialty is Pinot Noir. We took home a couple of bottles to put away.