I'm seeing lots of Darjeeling x Others stuff but nothing beats Darjeeling x Kay, for a pair that never even interacted once, they make a unique/special couple. This is the only pair I ship in GuP.
Midnightgunner: unfortunately, in the manga, whenever Yuu touches Haruka's breasts, Haruka freaks out and stops her. Even though Haruka is otherwise the main instigator of them making out.