Sonoma County is on the northwest coast of California, one of the northernmost parts of the greater San Francisco Bay Area. Its population at the 2000 census was 458,614. Its largest city and county seat is Santa Rosa. Sonoma is the southwestern county of California’s Wine Country region, which also includes Napa, Mendocino, and Lake counties. More than 7. 4 million tourists visit each year, spending more than $1 billion in 2006. Aside from the world renowned wineries Sonoma has an abundance of natural beauty to be explored and discovered. Start your visit here and get inspired to take advantage of all that Sonoma County has to offer.