We love the look of wood floors in a bathroom. We inherited a wood floor in ours — it was about the only thing we loved about the tiny, long and narrow space. One of the first things we did was repaint it white, and we struggled with the best choice of paint for a floor that would get wet in spots. Our neighbor, a vintage boat restorer, suggested a traditional (and local!) New England paint uniquely suited to this use...
Mike pointed out that using marine paint was a perfect choice for a wood bathroom floor because its tough as nails, made for boats and decks, and no stranger to getting wet. In particular, he recommended marine paint from George Kirby Jr.'s Paint Company, a locally made (Boston) boat paint which has been around for more than 150 years. We used a color called Yacht White (they can color match to any color) and we couldn't be happier. Over two years later it still looks as good as the day we painted it. We've talked to friends who painted their bathroom floor with Benjamin Moore's oil-based deck paints and are very pleased, so that would also be a good choice, although we love the idea of buying locally from a family-owned company.
As far as general maintenance tips for a painted-wood bathroom floor, we were advised that as long as we sealed around the tub, toilet and radiator really well and wiped up any puddles of water that might accumulate, the upkeep would be minimum. We haven't had to touch it since! Another great use for Marine Boat paint is to paint outside furniture such as Adirondack or patio chairs, since the rain won't bother it.
(Images: 1:Light Locations, 2-3: Living Etc.)