Just behind the New York Public Library [1] is Bryant Park, filled with pretty flower beds, gravel paths, a stylish indoor-outdoor restaurant, and lots of benches that are usually packed with office workers at lunchtime.
The park is named after poet and journalist William Cullen Bryant, a great proponent of parks and one of the people most responsible for the creation of Central Park [2].
Outdoor movies in the summer, free evening open air concerts in spring and fall, and scenic winter market filled with holiday stalls and ice skating rink make this a nice little four season escape.
Links:
[1] http://www.moon.com/destinations/new-york-city-long-island/manhattan/midtown/new-york-public-library
[2] http://www.moon.com/destinations/new-york-city-long-island/manhattan/central-park