Some of America's most exceptional wines are Chardonnays from Sonoma. Here, a day-by-day travel itinerary for the Chardonnay obsessed.

Sonoma County, next door to Napa Valley and about 35 miles north of San Francisco, is America's most exciting Chardonnay region. It also happens to be the most sprawling. Unlike smaller, more manicured Napa, Sonoma is a dramatic Rhode-Island-and-a-half of craggy ocean cliffs, TV-Western ranchland and shadowy redwood forests. Chardonnay vineyards are found all over this far-flung landscape, and they produce a wildly diverse group of wines. In Sonoma, you'll find everything from the creamy, buttery Chardonnays to the bright, lively, fruit-forward types and the big, blockbuster wines. (You'll also find good restaurants, luxurious hotels and a wealth of wine- and non-wine-related activities--as noted below.)

Sonoma Valley and Carneros

Sonoma and Napa begin at exactly the same place--above San Pablo Bay, the northernmost reach of San Francisco Bay, in an area named Los Carneros after the sheep that once grazed there. A region of gently rolling hills cooled by the bay's fogs and breezes, Carneros has a sometimes iffy climate that's perfect for Chardonnay, which ripens most evenly where conditions are challenging.

Though many of the better-known Carneros wineries are on the Napa Valley side, in Sonoma you'll find the old fieldstone winery Buena Vista, founded in 1857 by Hungarian impresario Count Agoston Haraszthy. Buena Vista makes two Carneros Chardonnays, including the very rich, pineapple-and-apple-inflected regular 1998 bottling and a graceful, soft, equally rich 1997 reserve. Other Carneros names to look for include the famous Durell and Sangiacomo vineyards, from which many prestigious wineries make first-rate vineyard-designated Chardonnays.

The town of Sonoma, located just north of Carneros, was where, back in 1823, Spanish friars first planted grapes and founded the Northern California wine business. Catch your breath there before heading to Sonoma Valley, also called the Valley of the Moon, a spectacular 25-mile crescent of sun-bathed khaki hills and tectonic knolls that runs roughly parallel to Napa Valley. In the southern part of Sonoma Valley, the bay and ocean breezes keep temperatures relatively cool, but the breezes don't reach the warm middle and upper portions of the Valley, in part because they are blocked by Sonoma Mountain. This midvalley heat gives many Sonoma Valley Chardonnays a fleshy, full-bodied density that can be tasted in wines such as St. Francis's value-priced ($14) 2000 Sonoma County Chardonnay. (Other top Chardonnay wineries in the area, such as Arrowood and Landmark, get some of their grapes from cooler regions.)

One of the region's most famous landmarks is Chateau St. Jean in Kenwood, the winery that pioneered the idea of single-vineyard Chardonnays way back in the 1970s. Because it uses grapes from throughout Sonoma, its newly refurbished tasting room offers a veritable tour of Sonoma Chardonnay: On any given day, visitors can taste current-release Chateau St. Jean wines like the 2000 Durell Vineyard Carneros ($24), with its toasty, tropical fruit notes; the 2000 Belle Terre Vineyard Alexander Valley ($24), subtly packed with notes of peach and honeydew; and the powerful 2000 Robert Young ($25), from the most famous grape grower in Alexander Valley. Chateau St. Jean also offers inexpensive ($10 to $35), hour-long wine courses by appointment; 10 bucks gets you a taste of three older wines in the Vineyard Room.

TRAVEL TIPS The old town square of Sonoma is a destination in itself, with numerous boutiques and restaurants, most notably The Girl & The Fig. Its wine list features Rhône-style bottlings from California and the world over. Also worth checking out: the well-marked, wooded trails of Jack London Historic State Park in Glen Ellen, which contains the ruins of the author's Wolf House. The massively refurbished Sonoma Mission Inn and Spa in Boyes Hot Springs is still the poshest place to chill out in the Valley. Its restaurant, Santé, is a prime meeting spot for Sonoma wine pros.

Chalk Hill, Sonoma Coast and the Russian River Valley

Driving north from Sonoma Valley and west toward the Pacific coast, you'll notice a change in climate, as madrones, oaks and eucalyptus give way to dark groves of redwood. Drive along Russian River's Bohemian Highway and you'll enter a part of Sonoma where the '60s never quite ended but where some of the country's most powerful establishment figures, such as Colin Powell and Clint Eastwood, gather every summer at the ultraprivate hideaway Bohemian Grove.

Some of the best wines from the region are just as elusive--Chardonnays from such cult-star local producers as Kistler, Williams Selyem, Dehlinger and Rochioli rarely make it to retail-store shelves. Right now the Russian River Valley is arguably California's trendiest Chardonnay region, although this is a relatively recent development. Russian River all but missed out on the first big Chardonnay boom in the early 1980s when fat-textured, high-alcohol blockbusters were the rage--not the more subtle, refined Russian River style. But when tastes grew more sophisticated and growers more confident, there was a rush to plant in cooler climates like Russian River.

Over the past 10 years, the spotlight has grown brighter and brighter on the Russian River Valley and Sonoma Coast to the north, with vineyards replacing apple orchards and showing up between seaside vacation homes. Although industry heavyweights like Gallo and Kendall-Jackson can be found here, it's still largely a region of small- to medium-size wineries focused on high-quality Chardonnay and Pinot Noir, such as Gary Farrell (who also serves as an informal consultant to Davis Bynum) and famed local vineyard Dutton Ranch, which supplies grapes to over two dozen top wineries and also turns out its own remarkably nuanced Dutton-Goldfield Chardonnay.

The appeal of these coastal-climate-influenced Chardonnays has led new pioneers to plant even farther north along the coast, among them Walt Flowers of Flowers winery and superstar wine consultant Helen Turley, who makes wine under her own Marcassin label as well as for the Russian River–based Martinelli family.

The Martinelli Winery in Windsor in many ways typifies the Russian River boom. The Martinellis didn't just follow the crowd; they've been in the Russian River Valley since 1895. Their tasting room, with its T-shirts, local jams and ceramics, has the folksy charm of old Sonoma. (You'll find Turley-made Martinelli bottlings but none of Turley's Marcassin mailing-list-only wines.) Try to taste the ripe, custardy Turley-made 2000 Martinelli Road Chardonnay and you'll find out what all the fuss is about.

A small pocket in the Russian River Valley now has its own appellation. Called Green Valley, it's the home of Iron Horse winery outside Sebastopol. If you arrive without an appointment, you'll be welcomed at its low-key tasting room, but if you make an appointment, you'll get a look at the whole operation and its commanding hilltop view.

TRAVEL TIPS The country roads of this region can plunge you into ancient redwood forest then pull you out high above the wave-lashed Sonoma coast and craggy Goat Rock Beach, where seals sun themselves on rocks. Dining options include Willow Wood Market Café in Graton, which serves an eclectic menu that features superfresh seafood and greens, as well as the Union Saloon in Occidental, where cowboys and '60s holdovers mingle cheerfully over locally made wine and beer. Finally, Applewood Inn & Restaurant is an oasis of luxe just a short drive from the awe-inspiring Armstrong Redwoods State Reserve.

Dry Creek Valley, Alexander Valley and Knights Valley

In the past decade or so, Healdsburg has morphed from a sleepy farm town into a quintessential California wine country village. Neither excessively slick nor exactly laid-back, it's arranged around a square straight out of It's a Wonderful Life--except that George Bailey never had such European-style breads and cappuccinos to choose from, or for that matter, such wine-celebrity sightings.

Healdsburg also happens to be the first stop en route to two of Sonoma's most famous wine regions: Dry Creek Valley to the west and Alexander Valley to the north. Dry Creek is best known for Zinfandel, but a drive to Ferrari-Carano offers not only a look at its lavish, massive, Italianate visitors' center but also a taste of its explosively flavored, tropical-fruited Chardonnay, made from Alexander Valley grapes. Ferrari-Carano's Chardonnay is in fact a fine introduction to the Alexander Valley style: opulent, fleshy, powerful and packed with fruit character. Drive up the Alexander Valley on Highway 101 almost any time of the year and you can feel the temperature rise as you reach the latitudes around Geyserville, midvalley. It's fine country for making rich red wines but also--thanks to arduous trial and error and careful site selection--gorgeous Chardonnays. Recent examples from grower Robert Young (who just produced his second estate wine) and Murphy-Goode offer proof.

Just south of Geyserville off Highway 101, Chateau Souverain is a fine place to stop. This rambling facility has a tasting room with a sizeable bar that cuts down on waiting time. There's an unusual depth of reserve and older wines for sale, as well as current releases like the polished, appley 2000 Chardonnay Sonoma County or the richer 2000 Winemaker's Reserve. The added draw here is the Café at the Winery, a white-tablecloth restaurant with soaring ceilings, an inventive menu and a humble name that hardly does the place justice. There always seems to be a food festival going on here--of truffles, say, or Cuban cooking. Wander in and you might get lucky.

With all the luminaries scrambling for coastal vineyard land, you might not expect Peter Michael winery, one of Sonoma's most admired Chardonnay producers, to have set up shop in the hot Knights Valley. But planting on high rocky hillsides can produce spectacular results, such as its vibrant 2000 Cuvée Indigene (price not yet determined).

TRAVEL TIPS Fortify yourself with fresh bread and pastry from the Downtown Bakery & Creamery in Healdsburg. Or, if it's lunchtime, wedge yourself into nearby Bistro Ralph, a sleek spot where you can drink the local wines and quite possibly rub elbows with the people who made them. The Jimtown Store near Healdsburg, a general store informed by the hip sensibilities of proprietor Carrie Brown, provides everything from gourmet deli sandwiches to antiques to classic baby boomer toys like Slinky. Just outside Healdsburg, the Madrona Manor is a handsome, private-feeling Victorian inn with a fine restaurant.

Richard Nalley writes the Wine Guide column for FOOD & WINE.