The Upper East Side is historically synonymous for New York's poshest residential neighborhood. That remains true today, but it also offers a wealth of other resource and residential options: apartment buildings for young professionals, lots of restaurants and bars, and New York's Museum Mile: that stretch of 5th Avenue that is home to some of the world's most interesting museums.
You can take the Second Avenue Q subway and 6, F subway lines to several different stops to get to the Upper East Side. The area also has a crosstown bus, so you can get across Central Park and to the other side of Manhattan easily.