Don't use just a solid black - it kills anything on it.
I used solid black for my lizard quilt and for the background of my bright Mardi Gras mask quilt, and both just look a bit "flat". A whole mass of BonB prints would be more interesting. Or if you want to use just one fabric how about one of the very dark Moda Marbles. There are a couple of VERY dark greens, and a gorgeous dark navy that is nearly black, and I love the aubergine colour too (odd as I don't like purple normally).
If you decide to have the pieces background why not randomly piece lots of different VERY dark colours (say purple, navy, black, brown, green but all really dark so that from a distance the illusion of "black" is created but up close the variations are there).