Open Daily/Weekends: Ahlgren, Burrell School, Byington, David Bruce, Regale, Silver Mountain
Appointment/Passport: Big Basin, Downhill, Loma Prieta, Muccigrosso, Muns, PM Staiger, Sonnet, Zayante
Unknown: Forest, Forty Stump, JM Barranti, Redwood Ridge, Windhover
Skyline Boulevard is aptly named since it runs along the top of the mountains, from Highway 84 to 17. South of 17 it eventually connects to Highway 152 (Hecker Pass Road), though a significant stretch of that is dirt track for which 4 wheel drive is advisable.
East of 17 there is a cluster of wineries. Burrell School is open daily from Thursday to Sunday from 11-5PM. Right next door is Regale, whose tasting room is open weekends from Noon-5:30PM. Further down the road Loma Prieta is open on Passport days and by appointment. Muns Vineyard is open by appointment only; for Passport events they typically pour at an alternate location.
5 minutes south of Summit Road is Silver Mountain. Currently open on Passport days and by appointment, the winery recently got approval to open on Saturday afternoons. As of May 2010 that approval is currently on hold pending appeal, so call first. The winery is also home to Sonnet who also pour on passport days. Nearby, the status of Barranti Vineyards is unknown. They were a small Pinot Noir producer from 2003 onwards, but nothing has been heard in the past 2 years.
West of 17 there isn't much until you get to Bear Creek Road. There you'll find David Bruce open daily from 12-5 and 11-5 at weekends. Close by, Byington is also open daily from 11-5PM. Byington is also home to Downhill Winery, who pours there on passport events and occasionally by appointment. Muccigrosso are also located nearby, but they typically pour for SCMWA events at alternate locations.
4 miles south of Highway 35 is Zayante Vineyards. They open for passport events and by appointment.
Further west in the Boulder Creek area you'll find Ahlgren open on Saturdays from Noon-4PM. P & M Staiger are SCMWA members who typically pour at an alternate location for passport events. Big Basin is open by appointment as well as passport events and certain open days through the year.
There are a few other wineries in the area whose status is currently unclear. Forty Stump and Windhover seem to be not yet open. Redwood Ridge is a wedding facility with its own vineyard.