I am shopping for a light to go over my island too. A design consultant at a lighting store told me this today. Rectangular Island she says go round so mix up the shapes. Diameter of fixture should be about a third of length of Island. This is much bigger than was thinking! Good luck

I think multiple round glass pendants would work well in the space. Visually they are unobtrusive and will give the space a fresh look without being too trendy.

http://www.shopcandelabra.com/regina-andrew-large-globe-pendent-in-nickel-finish