For Colonial Williamsburg, that means adding new facilities and new programs. The Colonial Williamsburg Foundation, which already runs the four-star Williamsburg Inn, 14 restaurants, and a pair of 18-hole golf courses, will now add a privately funded resort spa and health-evaluation facility targeted at corporate executives and other high-end customers. The facility will offer an intense daylong battery of tests to identify health issues (typical cost: $3,000). It's expected to open in 2006.

"People today, both leisure travelers and conference-goers - and conference business is very important to us - expect fitness and spa facilities to be available," says Campbell. "We also know that it's a plus for these kinds of places to offer a health-evaluation opportunity as well. If you don't have it, you are less competitive."

Colonial Williamsburg hopes these changes will also attract repeat business, a problem for many historical sites. The average visitor returns only every eight years. In addition, travelers are chopping their vacations into ever-smaller pieces, often bypassing historical destinations or trying to do them in a single day. Why visit the static estate at Mount Vernon when you can spend another day oohing and aahing over the high-tech wizardry at the Smithsonian's Air and Space Museum?

"People who stay for three days have a far richer experience than people who stay for one. And people who stay for three days are far more likely to come back than people who stay for one day," says Campbell. "People who stay for one day think they've seen it. They don't know what they've missed. So we're working hard at developing more effective orientation programs."