We ended up just hitting Sebastiani and Ravenswood with the kids, which took us about 3.5 hours roundtrip going at a snails pace, but I would think you could easily hit a couple more if you had the stamina 😉 Most of the trip was very safe and comfortable for kids. Once you get of the bike path and back onto the roads, we encountered very few cars. There were plenty of other casual cyclists doing the same thing.
Above, I’ve noted a few more that seemed doable from the map view. The longer horizontal trail I included in the official Sonoma Bike Path that starts at a huge park and ends at Sebastiani. Is didn’t seem to connect a rider to many wineries, but offers a nice connection from the Square to the park for a peaceful ride.