Stacey--- when are you coming to East Hampton?! I grew up out here!!!
My suggestions:
best pizza in NY: Lombardi's on Mott St.
Harlem-- St Pauls Chapel @ Columbia University {one of the prettiest churches in NYC}, Cathedral of St John the Divine, Sylvia's on Lenox Ave {NY's best soul food}, Apollo Theater.
Lincoln Center-- the fountains are beautiful at night
American Museum of Natural History-- very fun for *all* ages
Central Park-- go to "The Ramble"- 37 acres of woodlands; excellent bird-watching, the views from Belvedere Castle
Metropolitan Museum of Art
Guggenheim Museum
St Patrick's Cathedral
MoMa
5th Avenue for the luxury goods; if yer into that sorta thing
United Nations
Grand Central Terminal
Chrysler Building
Carnegie Hall
New York Public Library
Bryant Park
Rockefeller Center {Morrell's has a nice wine bar there}
Chelsea Piers, if you're into working out-- the most amazing gym/sports complex in the world
Empire State Buidling- day or night
Flatiron Building
Gramercy Park
Tompkins Square Park; my favorite in NYC
St. Marks Place {a street with nice shops, small cafes, downtown feel- very different from the Upper East Side...}
Little India: East 6th Street--- kick a$$ curry
McSorley's Old Ale House
Washington Square Park
75 1/2 Bedford St
Balducci's
Museum for African Art
Dean & Deluca
Delancey St & East Houston St
LES Tenement Museum
Chinatown
City Hall
walk across the Brooklyn Bridge at sunset
Staten Island ferry at night
Statue of Liberty
Century 21, across from WTC site
NYSE
Trinity Church
Coney Island and the famous "Cyclone" roller coaster in Brooklyn
Astoria, Queens for amazing Greek food
Beauty Bar-- martini and a manicure!
Angelika for foreign, art house, indie films
Bowlmor Lanes in Greenwich Village for day-glo bowling, chill-out DJ, tapas and cocktails
I personally stay away from Times Square, WTC site, 34th St/Herald Square {where the famous Macy's is} South Street Seaport.... I also don't go to many tourist sites unless I have guests in town; I enjoy taking them to place like Empire State Building, etc... But I prefer to show them the real NYC the guide books don't cover very often.
These are the sights I could think of. If you want to PM me, I can give you ideas on food, bars and clubs as well.
Great info in Time Out NY magazine {pick up one when you get here; theres alot of info in it.} Village Voice online is another great read.
Enjoy your time in the *BEST* city in the world- my home, no matter where I live.