WASHINGTON, D.C.-AREA small businesses are going to some extraordinary lengths to appeal to the millions of people who are attending Tuesday's presidential inauguration. 

In addition to featuring first family-themed cocktails such as the "Obamarita" and "sangria all Michelle," El Tamarindo, a Latin American restaurant in Northwest Washington, is staying open 24 hours a day up until Tuesday. Down the street, L'Enfant Café, a French bistro which is typically only open for dinner, is hosting a special brunch, while the Grill from Ipanema, also in the area, is hosting a neighborhood inaugural celebration.

"An event like this poses a huge opportunity for area businesses," says Lisa Duperier, president of AdamsMorgan MainStreet, a nonprofit organization dedicated to revitalizing local businesses in the Adams Morgan neighborhood of D.C. "Not only will business owners associate themselves with a historic event that has truly energized the nation, they'll have a chance to ring in extra sales."

The DC Chamber of Commerce estimates that area businesses will attract anywhere from $700 million to $1 billion in consumer spending over the four-day weekend. Maggie Daniels, an associate professor of tourism and events management at George Mason University in Fairfax, Va., thinks that number could edge even higher to around $1.5 billion.

While the extra cash could prove to be a major boon to struggling local businesses, the added man-hours of staying open late and ordering more inventory could offset a good portion of those gains, says Andrew Zimbalist, an economics professor at Smith College, in Northampton, Mass. "Generally speaking, the impacts of these mega-events tend to overstate the actual impact many times over," he says.

To prepare for the onslaught of customers, Jonathan Marlow, owner of NationwideCar.com, a limousine and private car service in Alexandria, Va., called in extra vehicles from surrounding cities. Scott Auslander, owner of Ventnor's Sports Cafe, a sports bar and restaurant in Adams Morgan, is paying staffers to work extra hours until the inauguration and he says he's never had to order this much food during the month of January. "It is really hard to obtain capital and lines of credit when you don't have 22 locations and huge inventories," says Auslander. "Hopefully, while [inaugural visitors] are here, they will want to check out local establishments like mine."

While it's easy to get swept away with the sales that big-named events like the World Series and Super Bowl attract, business owners also need to concentrate on creating long-lasting, and thus more valuable, customer relationships during this time, says Dominique M. Hanssens, a marketing professor at the University of California at Los Angeles's Anderson School of Management. A small retailer might host a stand at a local fair, for example. During a big-named sports event, a local sporting-goods store might issue coupons or discounts on future purchases. (Here's our story about how to market effectively around big events.)

Businesses should also appeal to their existing customers, says Holly Berkley, an interactive marketing consultant and guest lecturer at San Diego State University. For the inauguration, for example, she suggests business owners send an inauguration-inspired email to customers with a discount for valued customers and a "forward to a friend" option. "Promotions done online can be just as effective (if not more) and will cost businesses a quarter of other types of promotions," she says.

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("Starting Up," a weekly column written by Diana Ransom for smSmallBiz.com, follows entrepreneurs through the early stages of launching a business. Write to her at dransom@smartmoney.com.)