what color should i paint the wall in the living room?

[Ella]

we have a living room with a glass/black/silver entertainment center. a black and white couch with gray and white pillows, glass and pewter coffee/end tables. our dining room has a glass table with a pewter metal base and chairs with a cream fabric seat. i am not sure what color to paint the wall. his idea was to paint the back of the entertainment center black so it hides everything. he also wants to get hard wood floors which i think would be a bad idea with those colors. i think gray or black wall paint would be too depressing. HELP and thank you