Best Ways to Kill Time

There's a ton to do in NYC, however, whether it's between events or just a slow day you are bound to find yourself with some free time.  Depending on the weather, you need not despair, there are many ways out there to kill time.  The list below is a highlight of some easy to remember places, it excludes for the most part stores which are all over the place.

Time Warner Center
While strolling through this upscale vertical mall you'll have plenty to see from high-end clothing stores, to the Samsung experience to some of the top restaurants in the city.  When you get hungry you can head to Whole Foods in the lower level to have a snack - they have an area to sit. 
The Time Warner Center is a good stop to or from Central park, while heading north from Times Square or on your way to Lincoln Center - not to mention on a cold, hot or rainy day.
(Columbus Circle: 59th & Broadway Map)


Starbucks
Sometimes it feels like there is a Starbucks on every block, and in a few cases there are more than one.  Nonetheless, there is a Starbucks near pretty much every location you can think of, from the Empire State building, to Times Square to Lincoln Center.

Giant Bookstores
Manhattan is filled with bookstores and they are great place to kill some time. Much like Starbucks, there is one near most major locations.  A few of the best ones include:
Barnes & Noble: Lincoln Square (66th & Broadway) and Midtown (45th & 5th Avenue)
Borders: The Time Warner Center (59th & Broadway) and by Penn Station (31st & 7th Avenue)
The Strand: Union Square (Broadway and 12th Street)
Book Culture:  Columbia University/St. John the Divine/Morningside Heights (112th & Broadway)
Barnes & Noble and Borders all have coffee shops inside them as well.

Grand Central Terminal
Voluntarily spend time in a train station?  Well, NYC has one nice mass transit hub and this is it.  Head downstairs where you'll find a big food concourse with tables, and even a few giant chairs to sit while you wait. Map

Chelsea Market
Chelsea Market is a converted former factory for the National Biscuit Company which maintains the factory's former appearance but now includes bakeries, restaurants, dessert stores and other interesting stores.  Chelsea Market is also home to the Food Network, Google and other media companies.
Located at 15th & 9th Avenue, this is a great place to spend some time on your way to the Meatpacking District, the High Line, or Chelsea art galleries.  Map


Rockefeller Center
Head downstairs in Rock Center to visit the underground concourse where there are plenty of seats (although it can be very busy during weekday lunch time) some with a view of the Rock Center Ice Skating Rink.  There are a good selection of food (pricey though) including pizza, soup and sushi.  There is of course also a Starbucks. Map

Hotels

While most tourists will already be staying in a hotel and many New Yorker's wouldn't want to go to one, some hotels offer an interesting way to kill time. For example, visit the Times Square Marriott Marquis for some impressive views and a large lounge.

Parks
When the weather is nice you can spend some time in one of many parks:

Central Park - As you will most likely be visiting it anyway...
Bryant Park - Great place to stop off while exploring midtown (42nd & 6th Map)
Washington Square Park (Map), Madison Square Park (Map), etc...