For foliage colour, Waffle Plants (Strobilanthes alternata), Prayer Plants (Maranta leucoeura), Peacock Plants (Calathea spp.), Arrowhead Plants (Syngonium podophyllum) and Caladiums (Caladium spp.) all bring interesting leaf colour highlights into the bathroom. Many of these foliage plants are also sensitive to harsh light and dry air, making them perfect for your steamy bathroom.
Another benefit from growing plants in your bathroom is that periodically you can put them in the shower and give them a tepid rinse. This will wash dust off the leaves and help give the potting mix a good soaking.