O'Keeffe was a modernist who stressed simplification of subject matter and design of the image. Not "painterly," more craftsmanlike in style. Also painted abstractions in a similar vein.
Below are three of those paintings along with photographs.
She and Alfred Stieglitz lived in a 30th floor apartment here in 1925.
Shelton Hotel 1924, by Andrew Harmon. A fairly early example of set-back massing in conformity with recent city zoning laws.
Her most famous New York City painting.
American Radiator Building 1924, by John Howells and Raymond Hood. This is also a night view from across Bryant Park.
A Cubist feeling here. Buildings are splashed across the canvas in a kind of montage. Three flowers are added for some reason.
RCA Building1933, by Raymond Hood. This was nearing completion when the previous image was painted, so it's possible that O'Keeffe used it as inspiration for the main building in the painting.