Based on the above great wisdom, a conversation with Kaj, and a recognition that this is about people visiting and not "pound the miles" we're restructuring the event a little. This will keep the drive times down but still provide great scenic routes.
Sat: drive from Mendocino down Highway 1 to Point Arena, 35 miles, about an hour since it's hugging the coast. Tour the lighthouse and have lunch. I've stayed at the lighthouse before (now a b&b so I didn't have to light the big candle) and I know a good place for lunch there, people can order off the menu. From there take Mountain View Road over to Boonville. Another 30 miles, 60 min. Visit, and maybe tour, the Anderson Valley Brewing Company (great brewery!). Then back to Mendo for the night. Another 1 hr and 40 miles. So total day of 103 miles and under 3 hrs of drive time, broken into 3 sections. Great scenery and roads and plenty of social time.
Sunday:drive from Mendocino down Highway 1 to Elk, 16 miles, 30 minutes of same scenic route, Elk to Highway 128 via Greenwood Rd, another 30 min and 20 miles. The owner of the Boonville hotel is Porsche guy and he loves driving Greenwood Rd! So that's an hour drive before stopping at first winery. Then visit 3-4 wineries along 128. Back to Mendo for the night. 33 miles and 50 minutes, less if we work our way up 128. Not a bad road to drive after wine tasting. And we can get to the first winery in time to start tasting before 11 am!
Unfortunately Kaj is going to have to go taste all of the 25-30 wineries in the area to find the right ones for us. Tough job but he's up to the challenge.
How's that sound?