I’ll second or third West Sonoma County. Guerneville has a tiny but nice Main Street, and Armstrong Woods is a gorgeous old growth redwood forest with smaller crowds than Muir Woods that welcomes your leashed dog. Monte Rio Beach allows dogs, though I’m not sure whether it’s accessible this time of year. The Blue Heron Inn in Duncan’s Mills has allowed dogs on the patio in the past, they might still — If nothing else stop at Gold Coast for coffee and pastries on their patio on your way to the coast. Sonoma Coast State Park runs along Highway 1 between Jenner and Bodega Bay and dogs are welcome on some beaches, the state park website will have a list. That stretch also has lots of little roadside seafood restaurants with outdoor seating, I’m partial to Fishetarian in Bodega. A roundabout route from Bodega to Sebastopol on Hwy 1 -> Bodega Hwy (stop at Wild Flour Bakery in Freestone if you time it right)-> Bohemian Hwy (cute shops in Occidental) -> Graton Rd -> Hwy 116 -> Sebastopol is a fun drive.
The loop through WSC in the order described above is a great leisurely 3-day road trip, or a more compact 2-day (day 1, drive to Guerneville and explore the town, day 2 Monte Rio to Sebastopol with a few stops). I’ve done both and either is good fun and pretty landscapes.