From FAO Schwartz, you'll be at the SE corner of Central Park. There's a loop road that runs inside the park for ~6 miles, find this road (on foot, much better than carriage or pedicabs) and start exploring. There are numerous places to take a side path and turn back around, the whole 6 mile loop is a bit much unless you're running/biking.
We're supposed to get a couple inches of snow in the next few days, should make the park that much nicer if it sticks around through the weekend.
The High Line Park (elevated railroad tracks that have been converted into a small park) is also very nice (10th Ave and W 20th St).