It's all about the children
As mentioned in a previous blog of mine, capturing the perfect images of children sometimes means letting kids behave naturally to catch some great candid shots. Think of children exploring a beach at low tide and the expressions on their faces as they find a starfish or a small crab. What a great image this would make..
While I still believe candid shots of children create some truly memorable images, I have found that some pictures are better planned and posed (P&P) to correspond with the spring blooming of daffodils or to coincide with an early morning sunrise.
Luckily, my children are at an age where they can pose themselves and not take as much instruction from me.
Depending on what look you have in mind for the images of children, I would recommend you consider shooting some of the pictures with a zoom or telephoto lens (100mm or higher). This will allow you to zoom in and blur the background when you set the aperture at F6 or lower. This effect is better at blurring the background than shooting with a shorter lens and setting the aperture to the same number all while isolating your subject (in my opinion, which makes a much more memorable image). You can conduct a quick test to see this effect in practice by comparing two lenses (one short and one long) while keeping everything else the same (i.e. shutter speed, F/stop, subject, distance from the subject, etc.)
Whether you plan and pose your subjects or let the kids be kids, you will most definitely be happy with the images you capture.