Sonoma County, Calif.
More than a half-dozen bike operators run tours through the picturesque grapevine-smothered hills of Sonoma County. You can easily rent some wheels and pedal from winery to winery on your own, or sign on for any number of day trips.
Wine Country Bikes offers its Classic Dry Creek Valley Wine Country tour along small, rolling hills. You'll pedal about 25 miles (40 kilometers) over several hours, stopping at vineyards to inspect the vines and taste the wines. A locally sourced lunch is included [source: Wine Country Bikes].
More serious cyclists can sign on for Getaway Adventures' Velo 'n Vino tour. First, you'll ride 30 to 35 miles (48 to 56 kilometers) through the lush vineyards of the Dry Creek Valley, eventually rolling into Asti, a historic town that hosts a "Tour de Vine" ride in fall. Then, it's back in the saddle to roll through the equally scenic Alexander Valley of northern Sonoma County, home to more than 40 wineries, before arriving in Healdsburg, where you ditch your bike and go winery-hopping by van the rest of the afternoon [sources: Getaway Adventures, Alexander Valley, Asti Tour de Vine].