Purple has been my neutral/background color for a couple of years now. I especially love it with touches of orange and lime----and maybe hot pink and yellow too. And red and turquoise.
Made a monochromatic quilt a couple years ago, in all oranges. Laid it out, and....There was no focal point.....At the last minute, I put a small deep turquoise solid square in the center of each block and then my inside (first) border was the same turquoise. Made that quilt ZING!
Red, turquoise and black
30's repros (but not red!) with black
orange with any batiks
ocean/sand/sky colors