Warm colors have a way of leaping forward, so glass tiles in warm colors will automatically catch the eye of anyone who enters the bathroom. A streak of magenta has a semi-feminine touch, but tomato red will have a more cross-gender effect. For depth, vary the colors within the accent -- use multiple shades of one color in the same stripe. For example, use dark red and light red together. Combine some glass tiles that are opaque and others that are transparent.
Cool colors are recessive, meaning they push to the back. However, if the cool colors are the only touch of color in an otherwise black and white room, they'll still stand out. Rather than a stripe of glass tiles placed all the way around the room, consider replacing squares of black and white tiles with squares made up of multiple cool colored tiles. Like the warm colors, combine multiple shades of colors (such as multiple shades of blue or multiple shades of green) in one bathroom. Get creative -- if using blue glass tiles, experiment with tiles that seem to have a bronze patina.
Varying shades of gray won't exactly match black and white, but gray can still be a good fit for a black and white bathroom. Combine multiple shades of gray in one pattern to create visual interest. Look for glass tiles that have textures, or combine tiles that have transparent and opaque qualities.
Shake up the black and white pattern in your bathroom by installing much smaller black and white glass tiles. Install the black and white glass tiles in a series of stripes around the room. Alternatively, create a mosaic effect by installing a more creative pattern of tiles, such as zig-zag or diamond shapes.