Sorry it's taken me a while to finish this post. Life intervened, as they say....
Here's how we rearranged the room. This time for a focal point, I used the wardrobe (from IKEA). Since it's kind of high for a horizontal surface, the kids don't tend to put so much clutter on it. On top sits a dollhouse log cabin (since it has glass windows, I like to keep it up high) and a plant. The girls use the wardrobe for clothes (there's no closet in the room) and it's easy to close the doors when it's messy. As for the shelf for toys, I decided to use it as a room divider to section off my older daughter's art area. We painted the back green to match the walls and hung up artwork on it. It's still usually a messy area, but this time the shelf hides the mess instead of displaying it. :)
Probably an idea focal point for a child's room would be something large that contained no horizontal surfaces, such as a painting or a large plant (though plants have their own set of problems when used with kids.) Another tactic for keeping rooms looking clean (when "being clean" on all occasions is near impossible) is to locate the messy areas (the toy box, the desk, the dresser) in areas out of the immediate line of sight, usually on the wall behind the door or on the same side as the door.
You can create a focal point by painting a section of the wall and hanging it with a display of pictures. Resist the temptation to put a bulletin board or a chalk board as the focal point - it will quickly become messy! We have a magnetic board section for kids' artwork on the wall behind the desk (visible as the dark wall in the desk picture). A high shelf for special toys (like an heirloom china doll or a ship model) is another possibility.
Let your children in on the secret of focal points, and let them know that a good way to keep you happy as room-cleaning inspector is to a.) make the bed and b.) make sure the focal point is neat. And if they're able to handle making the bed, make the bed the focal point with a brightly-colored wall behind it, a mosquito-net canopy (we got ours from IKEA), or fabric hung on the wall behind it like a tapestry. Point out that they can make their rooms beautiful with a little daily effort on their point, and you're raising the next generation of house artists!