First I would paint the trim to match or at least be of the same hue is the porcelain fixtures---not white.
Then decide on what color of light you are going to stick with and how nice a color rendering index it will kick off. Incandescents, halogens and increasingly LEDs have great CRIs (apples look like apples, oranges look like oranges) but most flourescents do not unless you buy the more expensive full scpectrum bulbs. Temps 5,000 and above are proving to have a positive effect on mood disorders, concentration and fatigue. Consider the paint chips under the lighting you choose only since it is all you will have. I have posted these before but they are important.
How bold, or more appropriately, how deep you go with color will depend on how much light you will have. And also consider whether this is primarily a guest bathroom or if someone is going to be using it to apply makeup, do hair and nails, and other such things. Deep colors can wack skin tones without nicely rendered light.
The bathroom you pictured is very small. You might achieve something very dramatic painting it but also splashing color with nice fluffy towels hanging or even rolled up on little shelves.
Some know it is a personal design quest shared by many but not all. I hate automatically painting white box top ceilings on things. It dates back to the days of one gas light plunked in the middle of the room. I think white ceilings look especially goofy in a small room like that pictured and worse if you paint deep colored walls.