So, we trekked out to Harriman State Park in upstate New York. There, we hiked approximately 9.5 miles into and out of the rolling green mountains: following the Seven Hills Trail to the ridge of the Ramapo Torne, on through to the Sebago Trail and finally past the lovely Stony Brook on the Pine Meadow Trail before catching the train back. This not-so-little loop is in the south of the park (there are far more trails north, but you need a car), but nevertheless climbs up to some incredible panoramic views. This trail guide says it's 6.5 miles and takes about four hours. Now, I'm no expert by any means, but the loop that we took was infinitely longer because of the walk between the trailhead and the Sloatsburg train station. In other words: reserve your whole day for this!
After about a mile and a half walk to the Pine Meadow trailhead, we skipped over the babbling Stony Brook to hitch up with the Seven Hills path. This took us steadily upwards to an intersection with Hillburn-Torne-Sebago trail, and then across the ridge of the Ramapo Torne to the summit. At the top of Ramapo, there's an unreal panoramic view of the Torne Valley and Hillburn, which was amazing for a picnic lunch in the sun. We then headed back down (into and out of a few peaks and valleys via stone steps and wooden bridges) before meeting back up with the Pine Meadow Trail and Stony Brook at the end. More than just a walk in the woods, but the forest and mountain mix was a pleasant find for being so close to the city.
More links if you're so inclined: