This is a good overview of the precise hike I took. That website, incidentally, is more informative than the NY/NJ trail conference or the official interstate palisades commission website.
I took a NJ Transit bus ($1.70) over the bridge. I'm not sure it's actually faster than walking, but it is indubitable that it saves you from having to walk. I didn't appreciate this outbound as much as I would coming home, of course. You exit at what is called GW Plaza West , walk a couple of blocks back, cross a busy street, and there you are. (Just keep aiming for the bridge.) Technically, the Long Path begins in Fort Lee on the south side of the bridge; this is a relatively recent change.
The beginning of the trail is nothing spectacular. It's woods, so it's pleasant enough, and I encountered quite a few morning joggers. For about 11 of the next 12.7 miles, the Palisades Interstate Parkway will be close by on your left, at times only 10 feet away. On your right are the cliffs that made it a park in the first place. You can't see them, though, because you're on top of them.
About every mile or so there will a lookout where you can see Manhattan, then the Bronx, then Yonkers, along with the Hudson River in between. The bigger view spots have parking and in some cases amenities such as restrooms. Near the beginning is also St. Peters College, the only private land you'll encounter along the hike.
The trail then passes between two nature preserves. On the other side of the highway is a public preserve; between the trail and the Hudson is the Greenbrook Sanctuary. The Greenbook Sanctuary was marked "members only" on the map. In my imagination, this was a very elite organization, a club of Rockefeller descendants feeding ivory-billed grosbeak turtles out of Ming teacups. In fact, the organization had free newsletters at their gate, and it seems that you can become a member for the utterly reasonable price of $35. The trail as it passes through here is quite beautiful. It's also where I encountered my first modest hills. The trail is much prettier through here than it was at the start.
The trail maps show that the Zabreski ruins are coming up. They are only the best preserved of a series of old house foundations.
You are more than ⅔ of the way there when you reach the Women's Federation Monument. Women's clubs were instrumental in getting this area preserved. You can go inside and on top of the castle. At this point, you may notice that you are now farther from the road - the roar of traffic is almost entirely gone.
From here the trail gets hilly, including some enormous steps. The State Line Lookout is not, in fact, at the state line. A little farther, the Border Monument is apparently at or near the line. It was also a monumental disappointment. I may or may not have gotten lost around here. Tip; at the monument, turn right. It feels totally counterintuitive, but do it anyway. Now let us never speak of that again. The trail here has many stairs, and then hills without stairs. Then you pop out of the woods onto route 9W, at the entrance to Columbia's Lamont Observatory.
To get home, I had to play Frogger across the busy highway and wait for a Rockland Coach bus.(Google Maps doesn't pull this up as public transportation, FYI.) I told the driver I wanted to go to the GW Bridge, and he said the bus didn't go there, but it did go to "41st or the Plaza." I said, "the Plaza," hoping that it would mean what I just said, and indeed it did. (Fare: $2.70.)
This trail is by no means wilderness, but it is surprisingly nice given that it is a narrow stretch of land by a highway. It's also easy to get to from the city, and at a lower price tag than many other hikes.