Stu E.
Yelp
We decided to go with Pushpak Motors for a five hour tour in Sonoma. But not just any kind of tour.  We got to drive around on our own electric motorized trikes.  Kind of like the TukTuks you may have seen that are used to transport folks in some countries like India, only these were without a top so we got to enjoy the breeze and sun on a spectacularly beautiful day in Sonoma.  Howard was a great host to get us started and it's really notable that he and his partners donate a portion of proceeds from each person/customer to three area charities!  Pushpak is also very big on safety so there's helmets, a briefing and some training to ensure that everyone feels good about taking off on the adventure.   
It was a blast tooling around Sonoma - people stopped and looked at our group of six trikes and waved everywhere we went.   We visited historical sites, vineyards, incredibly upscale neighborhoods, a cheese shop for a tasting, we had a charcuterie-esque lunch, and also a couple of wineries where we did tastings.   
If possible, ask for David as your tour guide.  He was fantastic!   Smart, articulate, funny.  David is a long-time Sonoma resident and his brain contains a vast storehouse of knowledge about area history, grapes, winemaking, area weather, real estate prices, etc. 
This tour was THE highlight of our trip to the Napa/Sonoma area.  There is also a three hour tour but we were glad we opted for the extra two hours to see the upscale neighborhoods and to do another winery.   This is FUN FUN FUN!  We can't recommend this enough.  Thanks Howard and David.