Why does pony tell cherry just don't forget that some of us watch the sunset too?

In the Outsiders, the two groups have unequal lifestyles, attitudes, and financial situations, they nevertheless live in the same world, beneath the same sun.  The words “some of us watch the sunset” suggest to Cherry that although some of the greasers live up to the stereotype of greasers as rough and unrefined, some of them, like Ponyboy, have a keen appreciation for beauty—as keen as that of the richest socialite. By agreeing on the basic fact that rich and poor people look at the same sun, Ponyboy and Cherry take a small step toward a potential reconciliation between the rival gangs. This moment of concord comes early in the narrative, and its idealistic tone makes the rifts and violence to come all the more painful.