photo courtesy of www.futuristarchitecture.com
For a super minimalist, monochromatic look, like the one above from Futurist Architecture, try one of the three great area rug options from below.
Left - West Village
Middle - Mercury
Right - Hallen Dark Grey
photo courtesy of http://modernsanctuary.life/galleries
Or for a warm and relaxing, yet still contemporary look, like the one above from Modern Sanctuary, try one of these great options to go with your white or gray sectional.
Left - Fluxus Granite
Middle - Levi Grey/Beige
Right - Borior Snowfox