Windows can allow entry of natural light and air. But if you think your bathroom doesn't have enough ventilation, you can consider using an extractor fan. You need to choose the right size for the fan and you can do this by getting the volume of your room. Your room volume will be multiplied by the number of air changes needed in an hour which is 20 for bathroom. Then you purchase a fan that is appropriate for your bathroom that could provide the needed flow rate of air.
Bear in mind that kids are playful and are prone to slipping and bumping into things even if they are in the bathroom. Place safety products in the bathroom like anti-slipping mats and adhesive pads that stick to the bottom of the tub. Also place drain and faucet covers, you can choose covers that are also decorative. Have a cover clamp for your toilet. Just use plain white so that kids will not be curious in peeping into it and be put to danger.
Bathroom is a part of the house intended for private sanitation. It is also a place where we can loosen up our tired mind and body to isolate us away from stress. Immersing in a half-filled bathtub has been a custom for a few to relax after a long tiring day. People feel refreshed after taking a nice shower and feel comfortable after attending to their hygiene. Basically, there are plenty of things a bathroom can offer that its definition does not only limit to as for personal cleanliness or a word used to euphemize as a room containing a toilet, but a room vital for people to meet relaxation at its best. So you might want to consider adding up an extra effort to beautify your bathroom to maximize comfort, space and aesthetics.