The Seattle airport has estimated that 35 percent of the people coming through last year were 55 or older, said Perry Cooper, an airport spokesman. To serve this group and others, the airport has begun offering electric cart service between the airport’s light rail station and the terminal, so passengers don’t have to walk the few tenths of a mile. A service for travelers arriving on cruises from Alaska lets them send their luggage directly from the ship to their departing flight.

At Tampa International Airport, the proportion of older travelers is higher than national levels — 40 percent of adult travelers are 55 or older, said Danny Valentine, an airport spokesman.

During a large renovation and expansion project that was completed last year, the Tampa airport worked with the design firm HOK and Skanska, a construction company, to minimize walking distances and create an open layout so passengers could easily find their way to gates, restrooms and restaurants. Additional staff members were stationed throughout the terminal. “For older passengers,” Mr. Valentine said, “it’s important to have that human touch.”

Hotel companies like Marriott International say they are also keeping an eye on travel trends among older guests. Toni Stoeckl, vice president of distinctive select brands at Marriott International, said one of the brands, Element Hotels, was introducing “Studio Commons” later this year — units with four rooms positioned around a single common area. The concept was developed partly in response to a rise in multigenerational family trips. In the new rooms, he said, “baby boomers can have their own private room but still share a common living area with kids or grandkids.”

Smaller properties look at those needs, as well. Joanne Cunningham, director of sales and marketing at the Dunes Manor Hotel & Suites in Ocean City, Md., said some of the hotel’s guests had been visiting since the 1960s. The management wanted to make sure they could keep returning comfortably with children and grandchildren, so Dunes converted the top three of its 11 floors to rooms that would be friendly to older people, equipping them with showers instead of bathtubs, and fixtures and furnishings that are easier for older guests to use, like extra bright lamps with large visible outlets for electronics.