You can decorate your window seat to be as playful as this one. Choose the right colors plus add some stuff toys to the seat. This will make the window seat fun and playful.
The view on your window should also be included in the consideration of your decoration. Just like this picture, the decoration suits the sea view outside. The pale blue color and white is also the perfect choice.
Instead of having a one side window seat, you can divide it in two. Just like the picture above, place a drawer at the center to create a division. Now it does not only look like a window seat but also a comfortable sofa.