The famous Flatiron Building stands just at the edge of Gramercy - Union Square right below Madison Square Park. If you are interested in classic New York architecture, Madison Square Park is a place to visit. The streets surrounding Madison Square Park are all old fashioned and include preserved office buildings with wonderfully intricate facades.
If you are a history buff, don't miss the birthplace of Teddy Roosevelt, a lovely 4 floor brownstone on East 20th Street. The original building was demolished but it was rebuilt on the same spot and refurnished with much of the original furniture.
Union Square is a hangout for New York University and New School Students. The park is surrounded by lots of shopping and good food. There is a farmers market there four days a week which provides local New York produce, plants and baked goods. During the winter they have a holiday market where shops from all over the city set up stalls and sell all kinds of goods.
Gramercy - Union Square features a wide range of vacation rentals. The neighborhood has old lofts, brownstones and even high-rises. The neighborhood has easy access to subways including a cross-town line. In a limited number of cases you might find a vacation rental that offers access to Gramercy Park but if you cannot find one then there is still Union Square and Madison Square to enjoy.