“We want to be there when someone transforms the recommendations of their friends into booking a reservation,” said David Godsman, vice president for global Web services for Starwood Hotels. “If they press the ‘Like’ button, we want to start a conversation.” He said he viewed his company’s Facebook pages as a way to extend Starwood’s relationship with its customers “from the 10 days they stay with us, to all year long.” Starwood has Facebook pages for 1,000 hotel properties across its nine brands.

Hotels need to make sure that their booking engines can be found wherever the customer is, rather than asking the customer to search them out, said Glenn Withiam, a spokesman for Cornell’s School of Hotel Administration, which recently held a hotel industry conference that examined social media.

Offering reservations directly helps to keep the conversation between the hotel and its guests, Mr. Withiam said. He added that using social media to communicate took the relationship beyond the booking transaction. The hotel can find out what pillow guests prefer, the drinks they want in the minibar or the type of room they need. Personalized service can keep a guest coming back, he said, and that, in turn, helps hotels hold the line on room prices.

“Hotels need to demonstrate the value of staying with them,” Mr. Withiam said, because when the focus is just on the lowest price, the competition leads to fewer amenities, lower service levels and decreased customer satisfaction.

Mr. Withiam added that travelers were expecting trip-related services to be available on the new platforms. PhoCusWright, a travel research firm, has found that 13 percent of social-network users now shop for travel on those Web sites and 35 percent of mobile-phone users expect to book travel on their phones in the next year.

Axses Systems Caribbean, a company in Barbados, has helped about 30 small hotels and chains in Barbados and nearby make their reservations available on Facebook since early 2009. Ian Clayton, the chief executive of Axses, said he hoped that by offering reservations directly, while customers were excited by the property, his hotel clients would lose fewer bookings to online travel sites.

The online agencies — Expedia, Travelocity, Orbitz and Priceline among them — increased their share of total online hotel bookings to 46 percent last year from 41 percent in 2008, according to PhoCusWright. Douglas Quinby, senior director at the firm, attributed most of that increase to travelers’ greater price awareness and decreased business travel during the recession.

While those travel agencies can be great assets for hotels — allowing them to sell more rooms and to sell those rooms at a lower price without diminishing the hotel’s brand image — there are multiple drawbacks, Mr. Withiam said. Hotels make less money for rooms sold through an online travel agency than if customers had booked directly. Those customers may also start to think about meeting their travel needs through the online agency, rather than through the hotel, becoming in essence a customer with a relationship to the booking Web site and not the hotel.

Trump Hotel Collection has been offering Facebook reservations for around six months, and Ivanka Trump, executive vice president for development and acquisitions at the Trump Organization, even has a booking widget on her personal Facebook page. Ms. Trump said her company had an advantage in social media because “we are a personality-driven brand.” She added, “When I tweet out a hotel special, a million people see it.” Once guests have made reservations though Facebook, Ms. Trump said a hotel “attaché” contacted them to complete a “dossier” of their personal preferences, like the newspapers they wanted delivered, in-room amenities they required or particular room temperatures.

Jillian Carroll, a Facebook spokeswoman, said that the travel industry was a natural partner. “Travel is inherently social,” she said. Travelers have long asked their friends for hotel and restaurant recommendations, and then shared their impressions afterwards. In addition to making reservations, Ms. Carroll said, some travel-related companies used Facebook to respond to customer complaints, notify users of travel reviews posted by their friends or run sweepstakes to win a free hotel stay.

To help the companies refine their pages, Facebook offers analytics showing the aggregate demographic information of the people who “Like” a particular page. Companies can also discover the time of day that receives the most engagement and which actions spur more people to press the Like button.

Hotels are trying different ways to use the new media. Hyatt guests with smartphones can check in and check out with them. That means travelers can check in during the taxi ride from the airport and simply pick up keys at the front desk.

Hilton Worldwide estimates that about 615,000 customers have downloaded its mobile apps. Along with the ability to make or modify a reservation, it has offered new services like meals that are ready when guests arrive.

While at-your-fingertips booking and personalized service may be important to business travelers, there is no denying the bottom line. “All too often, travelers will leave a hotel Web site and look for a better rate in an online travel agency,” Mr. Clayton said. To entice customers to book directly via Facebook, some hotels are offering a guaranteed lowest price.

Using Facebook and smartphone apps, hotels hope to deepen or regain the relationships they had with customers and to raise the quality of their experiences when they check in. Attracting guests to book directly in new ways is a win for the hotel, said Mr. Withiam, from a financial, customer relationship and brand perspective.