I'm a big hiker, what's the best trail in Pine Plains?

The best trail in Pine Plains is almost certainly the one associated with Stissing Mountain. In Pine Plains, there's a park called Stissing Mountain Multiple Use Area; there's a trail to the top of the mountain, which is about 1,400 feet high.

The center of Pine Plains is essentially right at the foot of the mountain, so you can't miss it.