We’ve got a comprehensive guide to the Hudson River Greenway, but it’s worth pointing out some particularly wonderful running opportunities around its northern section. In addition to the path itself, there are three terrific additions alternatives in the riverside area between 163rd St. & 216th St.:
Fort Tyron Park: Over 8 miles of pathways in this unique, Olmsted-designed park. The Cloisters Museum is located here. The trails are a combination of lovely woods, lawns, and fields. There are also stairs all over the park, so a good opportunity to get those thighs burning! Great views of the Hudson River and Palisades. Also a large, accessible garden.
George Washington Bridge. It is possible to run over the George Washington Bridge! There is a sidewalk along the south side of the bridge open to cyclists on pedestrians. Fantastic views and quite a thrill as you run over to New Jersey. This link has specific instructions on how to access/egress the bridge on the NY and NJ sides. The distance (including access) is about 2 miles one-way, and hilly to access the bridge! Once on the NJ side, there’s nice running along Henry Hudson Dr. for about 2 miles — fairly shaded, with occasional water views.
The Fort Washington Park section of the Hudson River Greenway is also really nice, with great views lots of greenery.