There is a particular geometry on 5th Avenue between roughly 60th and 96th that almost no walking-route map captures correctly. The park side — that is, the west sidewalk, the one bordering Central Park — is overhung by the park’s perimeter tree line. American elms, London planes, the occasional honey locust, mature enough that the canopy spills west across 5th Avenue and onto the sidewalk itself. From about 9 AM, when the sun has cleared the East Side towers, until close to noon, you can walk a continuous half-mile of shade on the park side that does not exist on any other Manhattan avenue.
After noon the geometry collapses. The sun gets too high, the canopy doesn’t reach far enough, and the building-shade trick that works on the side streets doesn’t apply here because the buildings are on the wrong side. So this is a morning walk only. The picks below assume that.