Spill lists 7 wineries in Sonoma Valley that accept walk-ins without a reservation. Walk-ins are welcome at 7 of them. A typical tasting is $25. The wineries themselves maintain the facts on 2 of these pages.
Do I need a reservation to visit wineries in Sonoma Valley?
Not at the wineries on this page, which take walk-ins. Many other Sonoma Valley wineries are appointment-only, so if a specific winery isn't listed here, assume you should book ahead.