Buy yourself a sheet of plywood or gypsum board, get a sample of the paint you are thinking of using, paint the plywood/gyp and lean it up against one of the walls in your room. Actually seeing the paint is place is the best way to determine if you like it or no.

You probably don't know what color the shelves are. In order to use a white you need to match the shelves. You can sample Westhighland White, but it might be close, but not quite, so could end up looking wrong. You could go ahead with WW, but repaint the shelves so there's no clashing. You will probably have more luck with an off white. Look at Shoji White or Natural Choice. Be sure to sample against the fireplace as it will really determine what will work as much as the shelves do. The shelves at least can be repainted.