Four Sisters Inns has added its seventh Wine Country property, taking over the management of Napa's Milliken Creek Inn and Spa.

The Monterey-based company, which began at the landmark Green Gables Inn in Pacific Grove, expanded into Sonoma and Napa counties about 20 years ago. It now manages boutique inns in Sonoma, Glen Ellen and Healdsburg, plus two each in Napa and Yountville.

"We love the Sonoma and the Napa valleys," said Four Sisters President Shelley Post.

The seven Wine Country inns are among 14 that Four Sisters owns or manages in California. Each is unique for its architecture and offerings, Post said.

Both Milliken Creek and the Gaige House in Glen Ellen feature their own spas. The Healdsburg Inn overlooks the town plaza, and the stone and brick Maison Fleurie in Yountville is the oldest hotel in the Napa Valley, built in 1873.

"They each have their own personality," Post said.

The privately held Four Sisters gets its name from Post and her three sisters, whose parents purchased the Green Gables Inn on Monterey Bay in 1971. The Post family first turned the seaside Queen Anne-style inn back into a residence. But a few years later they began renting out rooms there.

Today Post is the last of the sisters to work in the business.

Tourism remains an important, growing segment of the Wine Country economy. Visitors to Sonoma County spent nearly $1.5 billion here in 2011, according to Visit California.

To date this year, county hotel revenues have increased 13 percent from 2012 and are projected to grow another 6 percent next year, said Ken Fischang, president/CEO of Sonoma County Tourism.

"Sonoma County is really positioned well for future growth," Fischang said.

The 14 Four Sisters inns primarily cater to leisure guests, though its Southern California properties also attract business travelers.

"We have many guests who have been coming for many, many years," Post said.

The inns have succeeded by appealing largely to guests seeking a break from the routine, she said, "a little getaway not too far from home."

Rates vary among properties, from about $180 to $795 a night, "and everything in between," Post said. Each inn features periodic special offers.

And guests often go on to visit other Four Sister properties.

"If you like one of our inns," Post said, "there's probably a pretty good chance you'll like one of the others."

Investors turn to Four Sisters to manage their properties partly because the company has provided "a very nice return to our owners," Post said.

Milliken Creek, the newest addition, recently was purchased by investors who asked Post's company to manage it.

The inn, on Silverado Trail in east Napa, features 12 rooms, some with marble baths, fireplaces and views of the adjacent Napa River. Guests are treated to full breakfast and evening wine and cheese tastings. Spa guests can choose from such treatments as couples aromatherapy massage and grapeseed body polish.

Along with the 14 Four Sisters-branded properties, the company manages two lodging properties in California for budget travelers, including the Sonoma Creek Inn in Boyes Hot Springs. At the other extreme, it manages Casa de Las Palapas, a five-bedroom seaside estate in Puerto Vallarta, Mexico, that features a pool, private beach, full-time cook and driver.