Another place to capture expressions are the subways; either on the platforms or in the cars themselves. My favorite images are the one of a young woman avidly watching a movie on her smartphone, while wearing a single hair roller to tame her fringe....and of the young girl who appears to be viewing a smart phone screen on an ad on a subway platform while her mother is busy texting on her real phone.
Besides the travel publications like National Geographic Traveler, Conde Nast Traveler, etc., the demand for this genre exists in industries like Travel, Photo Education, etc. Many travel photographers are today leading photo-tours through companies such as Intrepid Exposures, utilising their knowledge of unique travel locations, experience of working as professional photographers and using this to help travel enthusiasts take great travel images during their trips. Many others are doubling up as educators in the field of ambient light photography. Some of them are doing assignments which intrinsically use their strengths, e.g. shooting exteriors or interiors of buildings for architects and interior designers. Photographers like Steve McCurry are often commissioned to shoot commercial advertising work using their skills from travel and documentary photography to produce powerful advertising images.
When you really love photographing a certain subject, it shows in your work. If you've built a cohesive collection of images around a particular people or place, consider hanging it in a gallery or selling prints or photo books online. Share your work with artist's galleries in and around relevant locales until you find someone who bites. Southwestern USA photographer Brett Edge took it a step further and opened his own gorgeous fine art gallery in Moab, Utah. Photographer Vivienne Gucwa published a coffee table book featuring her New York City photography. Just getting started? Share your work online for exposure, and upload it to print-on-demand websites for effortless print sales.
Make use of people to give your images life and scale. If the facade of a particular building appeals to you, the picture may be that much better if you show people walking in front of it. They will give it scale and also let viewers know what sorts of people live there, how they dress, and the like. An outdoor café may be more interesting crowded with people than empty.