UPPER WEST SIDE
Traditionally viewed as Manhattan's last bastion of respectable, middle-class life, the Upper West Side is characterized by huge apartment buildings filled with married couples, boisterous markets choked with strollers and rollerbladers, and the more establishment collegiate crowd, the ones who still wear their fraternity sweatshirts.
UPPER EAST SIDE
Stately, dignified, and WASPy, the Upper East Side has always been Manhattan's most elite neighborhood. It was here that the Vanderbilts, the Astors, the Whitneys and the Hewitts built their mansions and made the area synonymous with wealth. Today, the area, bounded roughly by Fifth Avenue to the west, Lexington Avenue to the east, 60th Street to the south and 96th Street to the north, is still home to many of the world's richest and most powerful. Fittingly, the city's toniest shopping options are also here.
Though its heart is all business, nothing belts out "Manhattan" more dramatically than Midtown's famous cluster of skyscrapers: the Empire State Building (34th St., at Fifth Ave), the Chrysler Building (E. 43rd St., at Lexington Ave.), the Citicorp Tower (E. 52nd St., at Third Ave.) and the Met Life Building (Park Ave., at 45th St.). Oh, and that's not to exclude Rockefeller Center (between Fifth and Sixth Aves., from 45th to 49th Sts.) and the United Nations (First Ave., at 44th St.).
Often dismissed by tourists as too dangerous, Harlem is a huge chunk of the city, from 90th Street up to 178th, and from the Harlem River clear across to the Hudson. It does have some dangerous sections, as do most of New York's neighborhoods, but it also has some happening nightlife and restaurants, notable churches, and the city's greatest concentration of museums and landmarks of black culture. East Harlem, also known as "El Barrio," is one of the city's Hispanic sections.
BEST 4: OTHER NEIGHBORHOODS (DOWNTOWN)
It wasn't until the mid-'70s that this warehouse district was renamed SoHo, standing for South of Houston (bounded by Sixth Avenue to the west, Broadway to the east, Grand Street to the south and Houston Street to the north). Its rechristening was at the hands of its homesteading artists, who moved into the gigantic, cast-iron buildings for their cheap and enormous lofts. By the late '70s, SoHo had surpassed 57th Street as the center of the art world. Now that the galleries have moved en masse to Chelsea, SoHo has become a large open-air shopping mall, albeit with much trendier tenants than you'll find at your average buyplex.
Once home to, yes, meat packers and later to the scandalous sex trucks seen in the documentary "Gay Sex in the '70s" (lending new meaning to the name), this little neighborhood sandwiched between the West Village and Chelsea has been completely revitalized over the last 10 to 15 years, now boasting some of the city's hippest boutiques, eateries and nightspots. Watch for its further ascension when much-talked-about park The High Line opens at Gansevoort Street in 2008.
LOWER EAST SIDE
Though it's not uncommon for New York neighborhoods to undergo huge changes over time, few have done so more dramatically in recent years than the Lower East Side -- once almost exclusively a lower-class enclave for Eastern European Jews, then later for poor people of all ilks. In the early '90s, gentrification began pushing both south from the East Village and east from SoHo, culminating in a neighborhood that is today one of the city's hippest, having the most street cred. On weekends (especially at night), its streets are literally overtaken by cute, drunk, hetero youngfolk.
On the other end of the spectrum, Chinatown thankfully changes little through the march of time, except to get bigger. Home to the largest Chinese community in the Western Hemisphere (and still growing), Chinatown swallowed Little Italy nearly whole, and has been nibbling lately on the Lower East Side. A world unto its own, you'll see, smell, and if you're daring even taste things in New York's Chinatown that you're not likely to see, smell, or taste anywhere else this side of the Yangtze.