A modular light-emitting panel assembly has first and second light guides edge lit by respective light sources. Each light guide has a light input edge, opposed side edges, opposed major surfaces and a pattern of light extracting elements at at least one of the major surfaces. The light guides are juxtaposed with a side edge of the first light guide abutting a side edge of the second light guide at a seam and with the major surfaces nominally coplanar. Various embodiments of the panel assembly additionally include respective structures that reduce visibility of the seam when the light sources illuminate the panel assembly.