"It's at the forefront of their mind even if it's the middle of summer," said Bratsis, whose business is based in Foxborough, Mass.
Many of the families she photographs schedule a portrait because they are spending vacation with extended family from different parts of the country.
"They're saying: 'We're here. We're together. We're dressed up. We look good. Let's get a family portrait done,'" Bratsis said.
"It's something for them to remember that special time they spent together at the Cape."
Nicole Smith of Victoria started a business, Flytographer, dedicated to connecting travellers and professional photographers. Many of her clients use the photos on holiday cards, she said.
One of them was David Tjhio of Chicago, who arranged to have a photo session during a recent trip to Lisbon, Portugal, with his wife, Julie, because he wanted some candid photos.
"Most of our pictures are predictable sightseeing type of pictures," he said. Usually, he said, "if we're lucky, we can get someone to take a posed shot of the two of us."
Working with the photographer in a part of the city they wanted to tour was a great experience, he said. "It exceeded what I thought we would get," Tjhio said.
They intend to use one of the photos for a holiday greeting card — something new for them.
Elizabeth and Grant Moyer of Rye, New York, are using an image from their family photo session this summer in Florence, Italy, for their 2014 holiday card. Sharing the vacation makes the card more memorable than a posed shot at home, she said.
Children are often more co-operative during outdoor sessions than they would be in a studio, said Karen Seifert, co-owner of I Heart New York, which mostly photographs visitors to New York City. Many families book their session when they start planning their trip, she said. It's not uncommon for them to arrive in the city with co-ordinated outfits and plans for an exciting holiday card, she said.
Some travellers have come to view vacation photo shoots as another tourist opportunity, said Timothy Beckford, co-owner of I Heart New York.
"They see it as an activity — similar to a tour," he said. "We're another thing to do."