When designing kids rooms and nurseries we can be playful and crazy - it's important to create a friendly, healthy, creative space with lots of natural light.
This is a calming traditional nursery in white beige color scheme. Murals are so complementary to the room, they're not overwhelming at all. It's great to paint murals in kids rooms, but it's also very important to not go too crazy. I think this is a great example. They are also very cheap to make, if you have any drawing skills. However, if you plan to make murals, choose the painting wisely - accord the difficulty to your own skills. You can make an excellent simple mural or horrible complicated one, it's up to you (I vote for simple & lovely).
Black and brisk white color scheme make this kids room look fresh, open and tidy. Interesting bed design.
Here's a great idea for small spaces. If you plan to put a bunker bed, maybe you could try to make something like this - build-in bunker bed between wall and wall closet. It saves space, and looks great.
Now, one beach theme kids room. Room is completely white, only the few fabrics (curtains, bed cover) are in marine blue stripes. Some other details make it look like a little beach house, too (boats). Such cute, natural and not overcrowded space.
Next is a vintage inspired kids room, with such great color scheme (off white - firefighter red), and nice details. You may well use some of the decorating ideas - they're cheap and/or easy to make.